Accuracy the closeness of a single measurement to its true value

Acid (Arrhenius definition) a substance that produces hydrogen ions, H⁺ (hydronium ion, H₃O⁺ ), when it dissolves in water

Acid (Brønsted?Lowry definition) the species (molecule or ion) that donates a proton to another species in a proton-transfer reaction

Acid rain rain having a pH lower than that of natural rain, which has a pH of 5.6

Acid salt a salt that has an acidic hydrogen atom and can undergo neutralization with bases

Acid?base indicator a dye used to distinguish between acidic and basic solutions by means of the color changes it undergoes in these solutions

Acid?base titration curve a plot of the pH of a solution of acid (or base) against the volume of added base (or acid)

Acidic oxide an oxide that reacts with bases

Acid-ionization (or acid-dissociation) constant (K_a) the equilibrium constant for the ionization of a weak acid

Actinides elements in the last of the two rows at the bottom of the periodic table; actinium plus the 14 elements following it in the periodic table, in which the 5f subshell is filling

Activated complex (transition state) an unstable grouping of atoms that can break up to form products

Activation energy (Ea) the minimum energy of collision required for two molecules to react

Activity of a radioactive source the number of nuclear disintegrations per unit time occurring in a radioactive material

Activity series a listing of the elements in order of their ease of losing electrons during reactions in aqueous solution

Addition polymer a polymer formed by linking together many molecules by addition reactions

Addition reaction a reaction in which parts of a reactant are added to each carbon atom of a carbon?carbon double bond, which then becomes a C?C single bond

Adsorption the binding or attraction of molecules to a surface

Aerosol a colloid consisting of liquid droplets or solid particles dispersed throughout a gas

Ag⁺ Silver ion

Alcohol a compound obtained by substituting a hydroxyl group (—OH) for an —H atom on a tetrahedral (sp³ hybridized) carbon atom of a hydrocarbon group

Aldehyde a compound containing a carbonyl group with at least one H atom attached to it

Aliphatic hydrocarbon a saturated or unsaturated hydrocarbon; a hydrocarbon that does not contain benzene rings

Alkali metals the Group IA elements; they are reactive metals

Alkali metals the Group IA elements; they are reactive metals

Alkaline dry cell a voltaic cell that is similar to the Leclanché dry cell but uses potassium hydroxide in place of ammonium chloride

Alkaline earth metals the Group IIA elements; they are reactive metals, though less reactive than the alkali metals

Alkane an acyclic saturated hydrocarbon (one without a ring of carbon atoms); a saturated hydrocarbon with the general formula C_nH_2n+2

Alkene a hydrocarbon that has the general formula C_nH_2n and contains a carbon–carbon double bond

Alkyl group an alkane less one hydrogen atom

Alkyne an unsaturated hydrocarbon containing a carbon–carbon triple bond. The general formula is C_nH_2n-2

Allotrope one of two or more distinct forms of an element in the same physical state

Alloy a material with metallic properties that is either a compound or a mixture

Alpha emission emission of a nucleus, or alpha particle, from an unstable nucleus.

Amide a compound derived from the reaction of ammonia, or a primary or secondary amine, with a carboxylic acid

Amine a compound that is structurally derived by replacing one or more hydrogen atoms of ammonia with hydrocarbon groups

Amino acid a compound containing an amino group (—NH₂) and a carboxyl group (—COOH).

Amorphous solid a solid that has a disordered structure; it lacks the well-defined arrangement of basic units (atoms, molecules, or ions) found in a crystal

Ampere (A) the base unit of current in the International System (SI)

Amphiprotic species a species that can act as either an acid or a base (that is, it can either lose or gain a proton)

Amphoteric hydroxide a metal hydroxide that reacts with both bases and acids

Amphoteric oxide an oxide that has both acidic and basic properties

An approximate relation for a change of free energy of reaction with temperature

Angstrom (Å) a non-SI unit of length; 1 Å = 10^-10 m

Angular momentum quantum number (l) "also known as the azimuthal quantum number. The quantum number that distinguishes orbitals of given n having different shapes; it can have any integer value from 0 to n - 1."

Anion a negatively charged ion

Anode the electrode at which oxidation occurs

Antibonding orbitals molecular orbitals having zero values in the region between two nuclei and therefore concentrated in other regions

Aromatic hydrocarbon a hydrocarbon that contains a benzene ring or similar structural feature

Arrhenius equation the mathematical equation k = Ae^-Ea/RT, which expresses the dependence of the rate constant on temperature

Association colloid a colloid in which the dispersed phase consists of micelles

Atmosphere (atm) a unit of pressure equal to exactly 760 mmHg; 1 atm = 101.325 kPa (exact)

Atom an extremely small particle of matter that retains its identity during chemical reactions

Atomic mass as a general term, the mass of an individual atom; but usually we mean the average atomic mass for the naturally occurring element, expressed in atomic mass units

Atomic mass unit (amu) a mass unit equal to exactly one-twelfth the mass of a carbon-12 atom

Atomic number (Z) the number of protons in the nucleus of an atom

Atomic orbital a wave function for an electron in an atom; pictured qualitatively by describing the region of space where there is a high probability of finding the electron

Atomic symbol a one- or two-letter notation used to represent an atom corresponding to a particular element. A temporary name with a three letter notation (denoting the atomic number) is given to newly discovered elements

Atomic theory an explanation of the structure of matter in terms of different combinations of very small particles (atoms)

Avogadro?s law equal volumes of any two gases at the same temperature and pressure contain the same number of molecules

Avogadro’s number (N_A) the number of atoms in a 12-g sample of carbon-12, equal to 6.02 x 1023 to three significant figures

Avogadro's law equation V_m = specific constant (depending on T, P; independent of gas)

Axial direction one of two directions pointing from the center of a trigonal bipyramid along its axis






Band of stability the region in which stable nuclides lie in a plot of number of protons against number of neutrons

Band theory molecular orbital theory of metals

Bar a unit of pressure equal to 1 x 10⁵ Pa, slightly less than 1 atm

Barometer a device for measuring the pressure of the atmosphere

Base (Arrhenius definition) a substance that produces hydroxide ions, OH^-, when it dissolves in water

Base (Brønsted?Lowry definition) the species (molecule or ion) that accepts a proton in a proton-transfer reaction

Base pairing the hydrogen bonding of complementary bases

Base-ionization (or base-dissociation) constant (K_b) the equilibrium constant for the ionization of a weak base. Thus K_b for NH₃ is 1.8 x 10^-5

Basic oxide an oxide that reacts with acids

Bayer process a chemical procedure in which purified aluminum oxide, Al₂O₃, is separated from the aluminum ore bauxite

Bent geometry (angular geometry) nonlinear molecular geometry, in the case of a molecule of three atoms

Beta emission emission of a high-speed electron from an unstable nucleus

Bidentate ligand a ligand that bonds to a metal atom through two atoms of the ligand

Bimolecular reaction an elementary reaction that involves two reactant molecules

Binary compound a compound composed of only two elements

Binary hydride a compound that contains hydrogen and one other element

Binding energy (of a nucleus) the energy needed to break a nucleus into its individual protons and neutrons

Body-centered cubic unit cell a cubic unit cell in which there is a lattice point at the center of the unit cell as well as at the corners

Bohr’s formula for the energy of an electron in a hydrogen atom

Boiling point the temperature at which the vapor pressure of a liquid equals the pressure exerted on the liquid (atmospheric pressure, unless the vessel containing the liquid is closed)

Boiling-point elevation a colligative property of a solution equal to the boiling point of the solution minus the boiling point of the pure solvent

Boiling-point elevation equation ΔTb = K_bc_m

Bond energy the average enthalpy change for the breaking of a bond in a molecule in the gas phase

Bond length (bond distance) the distance between the nuclei in a bond

Bond order in a Lewis formula, the number of pairs of electrons in a bond

Bond order in molecular orbital theory, one-half the difference between the number of bonding electrons and the number of antibonding electrons

Bonding orbitals molecular orbitals that are concentrated in the regions between nuclei

Bonding pair an electron pair shared between two atoms

Boyle?s law the volume of a sample of gas at a given temperature varies inversely with the applied pressure

Boyle?s law equation

Brønsted?Lowry concept a concept of acids and bases in which an acid is the species donating a proton in a proton-transfer reaction, whereas a base is the species accepting a proton in such a reaction

Brønsted?Lowry concept a concept of acids and bases in which an acid is the species donating a proton in a proton-transfer reaction, whereas a base is the species accepting a proton in such a reaction

Buckminsterfullerene a molecular form of carbon (C₆₀) informally called “buckyball,” referring to its soccer-ball shape; a fullerene

Buffer a solution characterized by the ability to resist changes in pH when limited amounts of acid or base are added to it

Building-up principle (Aufbau principle) a scheme used to reproduce the electron configurations of the ground states of atoms by successively filling subshells with electrons in a specific order (the building-up order)






C₂H₃O₂^- Acetate ion

C₂O₄^2- Oxalate ion

Calorie (cal) a non-SI unit of energy commonly used by chemists, originally defined as the amount of energy needed to raise the temperature of 1 g of water by 1oC; now defined as 1 cal = 4.184 J (exact).

Calorimeter a device used to measure the heat absorbed or evolved during a physical or chemical change

Carboxylic acid a compound containing the carboxyl group, ?COOH, whose H atom is acidic

Catalysis the increase in rate of a reaction as the result of the addition of a catalyst

Catalyst a substance that increases the rate of reaction without being consumed in the overall reaction

Catalyst a substance that increases the rate of reaction without being consumed in the overall reaction

Catenation the covalent bonding of two or more atoms of the same element to one another

Cathode the electrode at which reduction occurs

Cathode rays the rays emitted by the cathode (negative electrode) in a gas discharge tube (tube of low-pressure gas through which an electric current is discharged)

Cation a positively charged ion

Cation exchange resin a resin (organic polymer) that removes cations from solution and replaces them with hydrogen ions

Cd²⁺ Cadmium ion

Cell potential the maximum potential difference between the electrodes of a voltaic cell

Cell reaction the net reaction that occurs in a voltaic cell.

Celsius scale the temperature scale in general scientific use. There are exactly 100 units between the freezing point and the normal boiling point of water.

Chain reaction, nuclear a self-sustaining series of nuclear fissions caused by the absorption of neutrons released from previous nuclear fissions

Change of state (phase transition) a change of a substance from one state to another

Charles?s law the volume occupied by any sample of gas at a constant pressure is directly proportional to the absolute temperature

Charles's law equation

Chelate a complex formed by polydentate ligands

Chemical bond a strong attractive force that exists between certain atoms in a substance

Chemical equation the symbolic representation of a chemical reaction in terms of chemical formulas

Chemical equilibrium the state reached by a reaction mixture when the rates of forward and reverse reactions have become equal

Chemical formula a notation that uses atomic symbols with numerical subscripts to convey the relative proportions of atoms of the different elements in a substance

Chemical kinetics the study of how reaction rates change under varying conditions and of what molecular events occur during the overall reaction

Chemical nomenclature the systematic naming of chemical compounds

Chemical property a characteristic of a material involving its chemical change

Chemical reaction (chemical change) a change in which one or more kinds of matter are transformed into a new kind of matter or several new kinds of matter

Chemical reaction (chemical change) "the rearrangement of the atoms present in the reacting substances to give new chemical combinations present in the substances formed by the reaction"

Chemisorption the binding of a species to a surface by chemical bonding forces

Chiral possessing the quality of handedness. A chiral object has a mirror image that is not identical to the object.

Chlor?alkali membrane cell a cell for the electrolysis of aqueous sodium chloride in which the anode and cathode compartments are separated by a special plastic membrane that allows only cations to pass through it

Chlor?alkali mercury cell a cell for the electrolysis of aqueous sodium chloride in which mercury metal is used as the cathode

Chromatography a name given to a group of similar separation techniques that depend on how fast a substance moves, in a stream of gas or liquid, past a stationary phase to which the substance may be slightly attracted

Claus process a method of obtaining free sulfur by the partial burning of hydrogen sulfide

Clausius–Clapeyron equation an equation that expresses the relation between the vapor pressure P of a liquid and the absolute temperature T: ln P = -ΔH_vap//RT + B, where B is a constant

ClO^- Hypochlorite ion

ClO₂^- Chlorite ion

ClO₃^- Chlorate ion

ClO₄^- Perchlorate ion

CN^- Cyanide ion

Co²⁺ Cobalt(II) ion or cobaltous ion

CO₃^2- Carbonate ion

Coagulation the process by which the dispersed phase of a colloid is made to aggregate and thereby separate from the continuous phase

Codon a sequence of three bases in a messenger RNA molecule that serves as the code for a particular amino acid

Colligative properties properties that depend on the concentration of solute molecules or ions in a solution but not on the chemical identity of the solute

Collision theory the theory that in order for reaction to occur, reactant molecules must collide with an energy greater than some minimum value and with proper orientation

Colloid a dispersion of particles of one substance (the dispersed phase) throughout another substance or solution (the continuous phase)

Combination reaction a reaction in which two substances combine to form a third substance

Combustion reaction a reaction of a substance with oxygen, usually with the rapid release of heat to produce a flame

Common-ion effect the shift in an ionic equilibrium caused by the addition of a solute that provides an ion that takes part in the equilibrium

Common-ion effect the shift in an ionic equilibrium caused by the addition of a solute that provides an ion that takes part in the equilibrium

Complementary bases nucleotide bases that form strong hydrogen bonds with one another

Complete ionic equation a chemical equation in which strong electrolytes (such as soluble ionic compounds) are written as separate ions in the solution

Complex (coordination compound) a compound consisting either of complex ions and other ions of opposite charge or of a neutral complex species

Complex ion an ion formed from a metal ion with a Lewis base attached to it by a coordinate covalent bond

Complex ion an ion formed from a metal ion with a Lewis base attached to it by a coordinate covalent bond

Compound a substance composed of two or more elements chemically combined

Compound a type of matter composed of atoms of two or more elements chemically combined in fixed proportions

Concentration a general term referring to the quantity of solute in a standard quantity of solvent or solution

Concentration a general term referring to the quantity of solute in a standard quantity of solvent or solution

Condensation the change of a gas to either the liquid or the solid state

Condensation polymer a polymer formed by linking many molecules together by condensation reactions

Condensation reaction a reaction in which two molecules or ions are chemically joined by the elimination of a small molecule such as water

Condensed (structural) formula a structural formula in which the bonds around each carbon atom are not explicitly written

Conjugate acid in a conjugate acid?base pair, the species that can donate a proton

Conjugate acid?base pair two species in an acid?base reaction, one acid and one base, that differ by the loss or gain of a proton

Conjugate base in a conjugate acid?base pair, the species that can accept a proton

Constitutional (structural) isomers isomers that differ in how the atoms are joined together

Constitutional (structural) isomers compounds with the same molecular formula but different structural formulas

Contact process "an industrial method for the manufacture of sulfuric acid. It consists of the reaction of sulfur dioxide with oxygen to form sulfur trioxide using a catalyst of vanadium(V) oxide, followed by the reaction of sulfur trioxide with water."

Continuous spectrum a spectrum containing light of all wavelengths

Control rods cylinders composed of substances that absorb neutrons, such as boron and cadmium, and can therefore slow a nuclear chain reaction

Conversion factor a factor equal to 1 that converts a quantity expressed in one unit to a quantity expressed in another unit

Coordinate covalent bond a bond formed when both electrons of the bond are donated by one atom

Coordination compound a compound consisting either of complex ions and other ions of opposite charge or of a neutral complex species

Coordination isomers isomers consisting of complex cations and complex anions that differ in the way the ligands are distributed between the metal atoms

Coordination number in a crystal, the number of nearest-neighbor atoms of an atom

Coordination number in a complex, the total number of bonds the metal atom forms with ligands

Copolymer a polymer consisting of two or more different monomer units

Corresponding oxoacid of ClO^- HClO

Corresponding oxoacid of ClO₂^- HClO₂

Corresponding oxoacid of ClO₃^- HClO₃

Corresponding oxoacid of ClO₄^- HClO₄

Corresponding oxoacid of CO₃^2- H₂CO₃

Corresponding oxoacid of NO₂^- HNO₂

Corresponding oxoacid of NO₃^- HNO₃

Corresponding oxoacid of PO₄^3- H₃PO₄

Corresponding oxoacid of SO₃^2- H₂SO₃

Corresponding oxoacid of SO₄^2- H₂SO₄

Corresponding oxoanion of H₂CO₃ CO₃^2-

Corresponding oxoanion of H₂SO₃ SO₃^2-

Corresponding oxoanion of H₂SO₄ SO₄^2-

Corresponding oxoanion of H₃PO₄ PO₄^3-

Corresponding oxoanion of HClO ClO-

Corresponding oxoanion of HClO₂ ClO₂-

Corresponding oxoanion of HClO₃ ClO₃-

Corresponding oxoanion of HClO₄ ClO₄-

Corresponding oxoanion of HNO₂ NO₂-

Corresponding oxoanion of HNO₃ NO₃-

Covalent bond a chemical bond formed by the sharing of a pair of electrons between atoms

Covalent network solid a solid that consists of atoms held together in large networks or chains by covalent bonds

Covalent radii values assigned to atoms in such a way that the sum of covalent radii of atoms A and B predicts an approximate A?B bond length

Cr₂O₇^2- Dichromate ion

Cr³⁺ Chromium(III) ion or chromic ion

Critical mass the smallest mass of fissionable material in which a chain reaction can be sustained

Critical pressure the vapor pressure at the critical temperature; it is the minimum pressure that must be applied to a gas at the critical temperature to liquefy it

Critical temperature the temperature above which the liquid state of a substance no longer exists regardless of the pressure

CrO₄^2- Chromate ion

Crystal a kind of solid having a regular three-dimensional arrangement of atoms, molecules, or ions

Crystal field splitting (Δ) the difference in energy between the two sets of d orbitals on a central metal ion that arises from the interaction of the orbitals with the electric field of the ligands

Crystal field theory "a model of the electronic structure of transition-metal complexes that considers how the energies of the d orbitals of a metal ion are affected by the electric field of the ligands"

Crystal lattice the geometric arrangement of lattice points of a crystal, in which we choose one lattice point at the same location within each of the basic units of the crystal

Crystal systems the seven basic shapes possible for unit cells; a classification of crystals

Crystalline solid a solid composed of one or more crystals; each crystal has a well-defined ordered structure in three dimensions

Cu+ Copper(I) ion or cuprous ion

Cu²⁺ Copper(II) ion or cupric ion

Cubic close-packed structure (ccp) a crystal structure composed of close-packed atoms (or other units) with the stacking ABCABCABCA. . . It has a face-centered cubic unit cell.

Curie (Ci) a unit of activity, equal to 3.700 x 10¹⁰ disintegrations per second

Cycloalkane a cyclic saturated hydrocarbon; that is, a saturated hydrocarbon in which the carbon atoms form a ring; the general formula is C_nH_2n

Cyclotron "a type of particle accelerator consisting of two hollow, semicircular metal electrodes, called dees (because the shape resembles the letter D), in which charged particles are accelerated by stages to higher and higher kinetic energies. Ions introduced at the center of the cyclotron are accelerated in the space between the two dees"






Dalton?s law of partial pressures the sum of the partial pressures of all the different gases in a mixture is equal to the total pressure of the mixture

Dalton’s law of partial pressures equation P = P_A + P_B + P_C . . .

d-Block transition elements those transition elements with an unfilled d subshell in common oxidation states

de Broglie relation

deca^- 10

Decomposition reaction a reaction in which a single compound reacts to give two or more substances

Defining equation for pH pH = -log [H₃O⁺]

Defining equation for the acid-ionization constant (K_a)

Defining equation for the base-ionization constant (K_b)

Degree of ionization the fraction of molecules that react with water to give ions

Delocalized bonding a type of bonding in which a bonding pair of electrons is spread over a number of atoms rather than localized between two

Denitrifying bacteria bacteria that use nitrate ion, NO₃^-, as a source of energy; they convert the ion to gaseous nitrogen

Density the mass per unit volume of a substance or solution

Deoxyribonucleic acid (DNA) the hereditary constituent of cells; it consists of two polymer strands of deoxyribonucleotide units

Deposition the change of a vapor to a solid

Desalinate remove ions from brackish (slightly salty) water or seawater, to make drinkable or industrially usable water

Deuterons nucleus of a hydrogen-2 atom

Dextrorotatory refers to a compound whose solution rotates the plane of polarized light to the right (when looking toward the source of light)

di^- 2

Diamagnetic substance a substance that is not attracted by a magnetic field or is very slightly repelled by such a field. This property generally means that the substance has only paired electrons.

Diffusion the process whereby a gas spreads out through another gas to occupy the space uniformly

Dimensional analysis (factor-label method) the method of calculation in which one carries along the units for quantities

Dipole moment a quantitative measure of the degree of charge separation in a molecule

Dipole?dipole force an attractive intermolecular force resulting from the tendency of polar molecules to align themselves such that the positive end of one molecule is near the negative end of another

Displacement reaction (single-replacement reaction) a reaction in which an element reacts with a compound, displacing another element from it

Dissociation constant of a complex ion (K_d) the reciprocal, or inverse, value of the formation constant

Distillation the process in which a liquid is vaporized then condensed; used to separate substances of different volatilities

Disulfide linkage a covalent linkage formed between two cysteine groups within a protein molecule by oxidation of the two groups

Double bond a covalent bond in which two pairs of electrons are shared by two atoms

Dow process a commercial method for isolating magnesium from seawater

Downs cell a commercial electrochemical cell used to obtain sodium metal by the electrolysis of molten sodium chloride






Effective nuclear charge the positive charge that an electron experiences from the nucleus, equal to the nuclear charge but reduced by any shielding or screening from any intervening electron distribution

Effusion the process in which a gas flows through a small hole in a container

Elastomer elastic or rubbery type of polymer

Electrochemical cell a system consisting of electrodes that dip into an electrolyte and in which a chemical reaction either uses or generates an electric current

Electrolysis the process of producing a chemical change in an electrolytic cell

Electrolyte a substance, such as sodium chloride, that dissolves in water to give an electrically conducting solution

Electrolytic cell an electrochemical cell in which an electric current drives an otherwise nonspontaneous reaction

Electromagnetic spectrum the range of frequencies or wavelengths of electromagnetic radiation

Electron a very light, negatively charged particle that exists in the region around the atom?s positively charged nucleus

Electron affinity the energy change for the process of adding an electron to a neutral atom in the gaseous state to form a negative ion

Electron capture the decay of an unstable nucleus by capturing, or picking up, an electron from an inner orbital of an atom

Electron configuration the particular distribution of electrons among available subshells

Electron volt (eV) the quantity of energy that would have to be imparted to an electron (whose charge is 1.602 x 10^-19 C) to accelerate it by one volt potential difference

Electronegativity a measure of the ability of an atom in a molecule to draw bonding electrons to itself

Element a substance that cannot be decomposed by any chemical reaction into simpler substances

Element A type of matter composed of only one kind of atom, each atom of a given kind having the same properties. (2.1) A substance whose atoms all have the same atomic number. (2.3)

Elementary reaction a single molecular event, such as a collision of molecules, resulting in a reaction

Empirical formula (simplest formula) the formula of a substance written with the smallest integer (whole-number) subscripts

Emulsion a colloid consisting of liquid droplets dispersed throughout another liquid

Enantiomers (optical isomers) isomers that are nonsuperimposable mirror images of one another

Endothermic process a chemical reaction or physical change in which heat is absorbed

Energy the potential or capacity to move matter

Energy levels specific energy values in an atom

Enthalpy (H) an extensive property of a substance that can be used to obtain the heat absorbed or evolved in a chemical reaction at constant pressure

Enthalpy (H) It equals the quantity U + PV.

Enthalpy of reaction (ΔH) the change in enthalpy for a reaction at a given temperature and pressure; it equals the heat of reaction at constant pressure

Entropy (S) a thermodynamic quantity that is a measure of how dispersed the energy of a system is among the different possible ways that a system can contain energy

Enzyme a protein that catalyzes a biochemical reaction

Equation for maximum work of a voltaic cell w_max = -nFE_cell

Equation for the first law of thermodynamics ΔU = q = w

Equation for the ion-product constant for water (K_w) K_w = [H₃O⁺][OH^- ] = 1.0 x 10-14 at 25°C

Equation relating entropy change to heat and temperature for an equilibrium process

Equation relating half-life and radioactive decay constant

Equatorial direction one of the three directions pointing from the center of a trigonal bipyramid to a vertex other than one on the axis

Equilibrium constant K_c the value obtained for the equilibrium-constant expression when equilibrium concentrations are substituted

Equilibrium constant K_c equation

Equilibrium constant K_p an equilibrium constant for a gas reaction, similar to K_c, but in which concentrations of gases are replaced by partial pressures (in atm)

Equilibrium-constant expression an expression obtained for a reaction by multiplying the concentrations of products, dividing by the concentrations of reactants, and raising each concentration term to a power equal to the coefficient in the chemical equation

Equivalence point the point in a titration when a stoichiometric amount of reactant has been added

Ester a compound formed from a carboxylic acid, RCOOH, and an alcohol, R'OH.

Ether a compound formally obtained by replacing both H atoms of H₂O by hydrocarbon groups R and R'

Exact number a number that arises when you count items or sometimes when you define a unit

Exchange (metathesis) reaction a reaction between compounds that, when written as a molecular equation, appears to involve the exchange of parts between the two reactants

Excited state a quantum-mechanical state of an atom or molecule associated with any energy level except the lowest, which is the ground state

Exothermic process a chemical reaction or physical change in which heat is evolved

Experiment an observation of natural phenomena carried out in a controlled manner so that the results can be duplicated and rational conclusions obtained






Face-centered cubic unit cell a cubic unit cell in which there are lattice points at the center of each face of the unit cell in addition to those at the corners

Faraday constant (F) the magnitude of charge on one mole of electrons, equal to 9.6485 x 10⁴C.

f-Block transition elements (inner transition elements) the elements with a partially filled f subshell in common oxidation states

Fe²⁺ Iron(II) ion or ferrous ion

Fe³⁺ Iron(III) ion or ferric ion

Fibrous proteins proteins that form long coils or align themselves in parallel to form long, water-insoluble fibers

First ionization energy (first ionization potential) "the minimum energy needed to remove the highest-energy (that is, the outermost) electron from a neutral atom in the gaseous state"

First law of thermodynamics the change in internal energy of a system, ΔU, equals q + w

First-order integrated rate law

Formal charge (of an atom in a Lewis formula) the hypothetical charge you obtain by assuming that bonding electrons are equally shared between bonded atoms and that the electrons of each lone pair belong completely to one atom

Formation constant (stability constant) of a complex ion (K_f) the equilibrium constant for the formation of a complex ion from the aqueous metal ion and the ligands

Formula defining mass percentage

Formula defining molality

Formula defining molarity

Formula defining mole fraction

Formula defining mole fraction (in terms of moles and also in terms of gas pressures)

Formula defining percentage yield

Formula for free energy in a nonstandard state given the reaction quotient ΔG = ΔGo + RT ln Q

Formula for pressure-volume work w = -PΔU

Formula for root-mean-square (rms) speed of molecules in a gas

Formula for the definition of density

Formula for the definition of kinetic energy

Formula for the energy of an emitted photon in terms of energy levels of an atom hν = -(E_f - E_i)

Formula for the mass percentage of solute

Formula mass (FM) the sum of the atomic masses of all atoms in a formula unit of a compound

Formula relating cell potential and reaction quotient at 25°C (Nernst equation)

Formula relating emperical formula mass to molecular mass

Formula relating enthalpy of reaction to standard enthalpies of products and reactants

Formula relating entropy of reaction to standard entropies of products and reactants ΔS° = ΣnS° (products) - ΣmS° (reactants)

Formula relating free energy and equilibrium constant ΔG° = -RT ln K

Formula relating free energy of reaction to standard free energies of products and reactants

Formula relating free-energy changes to enthalpy and entropy changes ΔH° = ΔH° - TΔS°

Formula relating heat to heat capacity q = C Δt

Formula relating heat to specific heat q = s x m x Δt

Formula relating intial molaritites and volumes to final molarities and volumes

Formula relating pH and pOH 14.00

Formula relating speed of light, frequency, and wavelength c = νλ

Formula relating standard cell potential and equilibrium constant at 25°C

Formula relating standard cell potential to standard electrode potentials

Formula relating standard free-energy change to the standard cell potential

Formula relating the acid-ionization and base-ionization constants K_aK_b = K_w

Formula to convert from degrees Celsius (t_C) to degrees Fahrenheit (t_F)

Formula to convert from kelvins (T_K) to degrees Celsius (t_C)

Formula unit the group of atoms or ions explicitly symbolized in the formula

Fraction of radioactive nuclei remaining after a specified period of time equation

Fractional (isotopic) abundance the fraction of the total number of atoms that is composed of a particular isotope

Fractional precipitation the technique of separating two or more ions from a solution by adding a reactant that precipitates first one ion, then another, and so forth

Frasch process a mining procedure in which underground deposits of solid sulfur are melted in place with superheated water, and the molten sulfur is forced upward as a froth using air under pressure

Free energy (G) a thermodynamic quantity defined by the equation G = H - TS

Freezing the change of a liquid to the solid state

Freezing point the temperature at which a pure liquid changes to a crystalline solid, or freezes

Freezing-point depression a colligative property of a solution equal to the freezing point of the pure solvent minus the freezing point of the solution

Freezing-point depression equation ΔT_f = K_bc_m

Frequency (ν) the number of wavelengths of a wave that pass a fixed point in one unit of time (usually one second)

Frequency factor the symbol A in the Arrhenius equation, assumed to be a constant

Fuel cell essentially a battery, but it differs by operating with a continuous supply of energetic reactants, or fuel

Fuel rods the cylinders that contain fissionable material for a nuclear reactor

Fullerene a family of molecules consisting of a closed cage of carbon atoms arranged in pentagons as well as hexagons

Functional group a reactive portion of a molecule that undergoes predictable reactions

Functional group a reactive portion of a molecule that undergoes predictable reactions






Gamma emission emission from an excited nucleus of a gamma photon, corresponding to radiation with a wavelength of about 10^-12 m

Gamma photon a particle of electromagnetic radiation of short wavelength (about 1 pm, or 10^-12 m) and high energy

Gas the form of matter that is an easily compressible fluid; a given quantity of gas will fit into a container of almost any size and shape

Gas chromatography a chromatographic separation method in which a gaseous mixture of vaporized substances is separated into its components by passing the mixture through a column of packing material. Substances in the gaseous mixture are attracted, to the packing material to different extents and thus move through the column at different rates.

Geiger counter a kind of ionization counter used to count particles emitted by radioactive nuclei. It consists of a metal tube filled with gas, such as argon.

Gene a sequence of nucleotides in a DNA molecule that codes for a given protein

Geometric isomers isomers in which the atoms are joined to one another in the same way but differ because some atoms occupy different relative positions in space

Glass electrode a compact electrode used to determine pH by cell potential measurements

Globular proteins proteins in which long coils fold into compact, roughly spherical shapes

Goldschmidt process a method of preparing a metal by reduction of its oxide with powdered aluminum

Graham?s law of effusion the rate of effusion of gas molecules from a particular hole is inversely proportional to the square root of the molecular weight of the gas at constant temperature and pressure

Graham's law of effusion equation (same container at constant T, P)

Gravimetric analysis a type of quantitative analysis in which the amount of a species in a material is determined by converting the species to a product that can be isolated completely and weighed

Ground state a quantum-mechanical state of an atom or molecule associated with the lowest energy level. States associated with higher energy levels are called excited states.

Group (of the periodic table) the elements in any one column of the periodic table






H₂PO₄^- Dihydrogen phosphate ion

Haber process an industrial process for the preparation of ammonia from nitrogen and hydrogen with a specially prepared catalyst, high temperature, and high pressure

Haber process an industrial process for the preparation of ammonia from nitrogen and hydrogen with a specially prepared catalyst, high temperature, and high pressure

Half-cell the portion of an electrochemical cell in which a half-reaction takes place

Half-life (t_1/2) the time it takes for one-half of the nuclei in a sample to decay

Half-life of a first-order rate law

Half-life of a second-order rate law

Half-life of a zero-order reaction

Half-reaction one of two parts of an oxidation?reduction reaction, one part of which involves a loss of electrons (or increase of oxidation number) and the other a gain of electrons (or decrease of oxidation number)

Hall–Héroult process the commercial method for producing aluminum by the electrolysis of a molten mixture of aluminum oxide in cryolite, Na₃AlF₆

Halogens the Group VIIA elements; they are reactive non-metals

HCO₃^- Hydrogen carbonate ion (or bicarbonate ion)

Heat the energy that flows into or out of a system because of a difference in temperature between the thermodynamic system and its surroundings

Heat capacity (C) the quantity of heat needed to raise the temperature of a sample of substance one degree Celsius (or one kelvin)

Heat of fusion (enthalpy of fusion) the heat needed for the melting of a solid

Heat of reaction the heat absorbed (or evolved) during a chemical reaction; it equals the value of q required to return the chemical system to a given temperature at the completion of the reaction

Heat of solution the heat absorbed (or evolved) when an ionic substance dissolves in water

Heat of vaporization (enthalpy of vaporization) the heat needed for the vaporization of a liquid

Henderson–Hasselbalch equation an equation relating the pH of a buffer for different concentrations of conjugate acid and base:

Henry?s law the solubility of a gas is directly proportional to the partial pressure of the gas above the solution

Henry's law formula S = k_HP

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Hess?s law of heat summation for a chemical equation that can be written as the sum of two or more steps, the enthalpy change for the overall equation equals the sum of the enthalpy changes for the individual steps

Heterogeneous catalysis the use of a catalyst that exists in a different phase from the reacting species, usually a solid catalyst in contact with a gaseous or liquid solution of reactants

Heterogeneous equilibrium an equilibrium that involves reactants and products in more than one phase

Heterogeneous mixture a mixture that consists of physically distinct parts, each with different properties

Heteronuclear diatomic molecules molecules composed of two different nuclei

hexa- 6

Hexagonal close-packed structure (hcp) "a crystal structure composed of close-packed atoms (or other units) with the stacking ABABABA . . .; the structure has a hexagonal unit cell"

Hg²⁺ Mercury(II) ion or mercuric ion

Hg₂²⁺ Mercury(I) ion or mercurous ion

High-spin complex ion a complex ion in which there is minimum pairing of electrons in the orbitals of the metal atom

Homogeneous catalysis the use of a catalyst in the same phase as the reacting species

Homogeneous equilibrium an equilibrium that involves reactants and products in a single phase

Homogeneous mixture (solution) a mixture that is uniform in its properties throughout given samples

Homologous series a series of compounds in which one compound differs from a preceding one by a fixed group of atoms, for example, a —CH₂ — group

Homonuclear diatomic molecules molecules composed of two like nuclei

Homopolymer a polymer whose monomer units are all alike

HPO₄^2- Monohydrogen phosphate ion

HSO₃^- Hydrogen sulfite ion (or bisulfite ion)

HSO₄^- Hydrogen sulfate ion (or bisulfate ion)

Hund?s rule the lowest-energy arrangement of electrons in a subshell is obtained by putting electrons into separate orbitals of the subshell with the same spin before pairing electrons

Hybrid orbitals orbitals used to describe bonding that are obtained by taking combinations of atomic orbitals of the isolated atoms

Hydrate a compound that contains water molecules weakly bound in its crystals

Hydration the attraction of ions for water molecules

Hydrocarbons compounds containing only carbon and hydrogen

Hydrocarbons compounds containing only carbon and hydrogen

Hydrogen bonding a weak to moderate attractive force that exists between a hydrogen atom covalently bonded to a very electronegative atom and a lone pair of electrons on another small, electronegative atom. It is represented in formulas by a series of dots

Hydrologic cycle the natural cycle of water from the oceans to fresh water sources and back to the oceans

Hydrolysis the reaction of an ion with water to produce the conjugate acid and hydroxide ion or the conjugate base and hydrogen ion

Hydronium ion the H₃O⁺ ion; also called the hydrogen ion and written H⁺ (aq)

Hydrophilic colloid a colloid in which there is a strong attraction between the dispersed phase and the continuous phase (water)

Hydrophobic colloid a colloid in which there is a lack of attraction between the dispersed phase and the continuous phase (water)

Hypothesis a tentative explanation of some regularity of nature






Ideal gas law the equation PV = nRT, which combines all of the gas laws

Ideal gas law equation PV = nRT

Ideal solution a solution of two or more substances each of which follows Raoult?s law

Immiscible fluids fluids that do not mix but form separate layers

Inequality relating entropy change to heat and temperature for a spontaneous process

Initiator a compound that produces free radicals in a reaction for the preparation of an addition polymer

Inner transition elements the two rows of elements at the bottom of the periodic table

Inner transition elements the elements with a partially filled f subshell in common oxidation states

Inner transition elements the elements with a partially filled f subshell in common oxidation states

Inorganic compounds compounds composed of elements other than carbon. A few simple compounds of carbon, including carbon monoxide, carbon dioxide, carbonates, and cyanides, are generally considered to be inorganic.

Integrated rate law a mathematical relationship between concentration and time

Intermolecular forces the forces of interaction between molecules

Internal energy (U) the sum of the kinetic and the potential energies of the particles making up a system

Internal energy (U) the sum of the kinetic and the potential energies of the particles making up a system

International System of Units (SI) a particular choice of metric units that was adopted by the General Conference of Weights and Measures in 1960

Ion an electrically charged particle obtained from an atom or a chemically bonded group of atoms by adding or removing electrons

Ion exchange a process in which a water solution is passed through a column of a material that replaces one kind of ion in solution with another kind

Ion product (Q_c) the product of ion concentrations in a solution, each concentration raised to a power equal to the number of ions in the formula of the ionic compound

Ionic bond a chemical bond formed by the electrostatic attraction between positive and negative ions

Ionic compound a compound composed of cations and anions

Ionic radius a measure of the size of the spherical region around the nucleus of an ion within which the electrons are most likely to be found

Ionic solid a solid that consists of cations and anions held together by the electrical attraction of opposite charges (ionic bonds)

Ionization energy the energy needed to remove an electron from an atom (or molecule). Often used to mean first ionization energy.

Ion-product constant for water (K_w) the equilibrium value of the ion product [H3O⁺][OH^-].

Ion-selective electrode an electrode whose cell potential depends on the concentration of a particular ion in solution

Isoelectronic refers to different species that have the same number and configuration of electrons

Isomers compounds of the same molecular formula but with different arrangements of the atoms

Isotope dilution a technique to determine the quantity of a substance in a mixture or the total volume of solution by adding a known amount of an isotope to it

Isotopes atoms whose nuclei have the same atomic number but different mass numbers; that is, the nuclei have the same number of protons but different numbers of neutrons






Joule (J) the SI unit of energy; 1 J = 1 kg × m²/s²






Kelvin (K) the SI base unit of temperature; a unit on the absolute temperature scale

Ketone a compound containing a carbonyl group with two hydrocarbon groups attached to it

Kilogram (kg) the SI base unit for mass; equal to about 2.2 pounds

Kinetic energy the energy associated with an object by virtue of its motion

Kinetic-molecular theory (kinetic theory) the theory that a gas consists of molecules in constant random motion






Lanthanides the first of the two rows of elements at the bottom of the periodic table; lanthanum plus the 14 elements following it in the periodic table, in which the 4f subshell is filling

Laser a source of intense, highly directed beam of monochromatic light; the word laser is an acronym meaning light amplification by stimulated emission of radiation

Lattice energy the change in energy that occurs when an ionic solid is separated into isolated ions in the gas phase

Lattice energy the change in energy that occurs when an ionic solid is separated into isolated ions in the gas phase

Law a concise statement or mathematical equation about a fundamental relationship or regularity of nature

Law of combining volumes a relation stating that gases at the same temperature and pressure react with one another in volume ratios of small whole numbers

Law of conservation of energy energy may be converted from one form to another, but the total quantity of energy remains constant

Law of conservation of mass the total mass remains constant during a chemical change (chemical reaction)

Law of definite proportions (law of constant composition) a pure compound, whatever its source, always contains definite or constant proportions of the elements by mass

Law of mass action the values of the equilibrium-constant expression K_c are constant for a particular reaction at a given temperature, whatever equilibrium concentrations are substituted

Law of multiple proportions when two elements form more than one compound, the masses of one element in these compounds for a fixed mass of the other element are in ratios of small whole numbers

Le Châtelier?s principle when a system in equilibrium is disturbed by a change of temperature, pressure, or concentration variable, the system shifts in equilibrium composition in a way that tends to counteract this change of variable

Le Châtelier?s principle when a system in equilibrium is disturbed by a change of temperature, pressure, or concentration variable, the system shifts in equilibrium composition in a way that tends to counteract this change of variable

Lead storage cell a voltaic cell that consists of electrodes of lead alloy grids; one electrode is packed with a spongy lead to form the anode, and the other is packed with lead dioxide to form the cathode

Levorotatory refers to a compound whose solution rotates the plane of polarized light to the left (when looking toward the source of light)

Lewis acid a species that can form a covalent bond by accepting an electron pair from another species

Lewis base "a species that can form a covalent bond by donating an electron pair to another species."

Lewis electron-dot formula a formula in which dots are used to represent valence electrons

Lewis electron-dot symbol a symbol in which the electrons in the valence shell of an atom or ion are represented by dots placed around the letter symbol of the element

Ligand a Lewis base that bonds to a metal ion to form a complex ion

Ligand a Lewis base that bonds to a metal ion to form a complex ion

Limiting reactant (limiting reagent) the reactant that is entirely consumed when a reaction goes to completion

Line spectrum a spectrum showing only certain colors or specific wavelengths of light

Linear geometry a molecular geometry in which all atoms line up along a straight line

Linkage isomers isomers of a complex that differ in the atom of a ligand that is bonded to the metal atom

Lipids biological substances like fats and oils that are soluble in organic solvents, such as chloroform and carbon tetrachloride

Liquefaction the process in which a substance that is normally a gas changes to the liquid state

Liquid the form of matter that is a relatively incompressible fluid; a liquid has a fixed volume but no fixed shape.

Liter (L) a unit of volume equal to a cubic decimeter (equal to approximately one quart)

Lithium?iodine battery a voltaic cell in which the anode is lithium metal and the cathode is an I₂ complex.

Logarithmic form of the Arrhenius equation expressed at two temperatures

London forces (dispersion forces) the weak attractive forces between molecules resulting from the small, instantaneous dipoles that occur because of the varying positions of the electrons during their motion about nuclei

Lone pair (nonbonding pair) an electron pair that remains on one atom and is not shared

Low-spin complex ion a complex ion in which there is more pairing of electrons in the orbitals of the metal atom than in a corresponding high-spin complex ion

Magic number the number of nuclear particles in a completed shell of protons or neutrons

Magnetic quantum number (m_l) the quantum number that distinguishes orbitals of given n and l—that is, of given energy and shape—but having a different orientation in space; the allowed values are the integers from -l to +l

Main-group element (representative element) an element in an A column of the periodic table, in which an outer s or p subshell is filling

Main-group element (representative element) an element in an A column of the periodic table, in which an outer s or p subshell is filling

Manometer a device that measures the pressure of a gas or liquid in a sealed vessel

Markownikoff?s rule a generalization stating that the major product formed by the addition of an unsymmetrical reagent such as H?Cl, H?Br, or H?OH is the one obtained when the H atom of the reagent adds to the carbon atom of the multiple bond that already has the greater number of hydrogen atoms attached to it

Mass the quantity of matter in a material

Mass defect the total nucleon mass minus the atomic mass of a nucleus

Mass number (A) the total number of protons and neutrons in a nucleus

Mass percentage parts per hundred parts of the total, by mass

Mass percentage of solute the percentage by mass of solute contained in a solution

Mass spectrometer an instrument, such as one based on Thomson?s principles, that measures the mass-to-charge ratios of atoms

Mass-energy equivalence equation ΔE = (Δm)c²

Mass-energy equivalence equation ?E = (Dm)c2

Material any particular kind of matter

Matter "all of the objects around you (1.1); whatever occupies space and can be perceived by our senses. (1.3)"

Maxwell?s distribution of molecular speeds a theoretical relationship that predicts the relative number of molecules at various speeds for a sample of gas at a particular temperature

Melting (fusion) the change of a solid to the liquid state

Melting point the temperature at which a crystalline solid changes to a liquid, or melts

Messenger RNA a relatively small RNA molecule that can diffuse about the cell and attach itself to a ribosome, where it serves as a pattern for protein synthesis

Metal a substance or mixture that has a characteristic luster, or shine, is generally a good conductor of heat and electricity and is malleable and ductile

Metal a substance or mixture that has a characteristic luster, or shine, is generally a good conductor of heat and electricity and is malleable and ductile

Metal refining in metallurgy, the purification of a metal

Metallic solid a solid that consists of positive cores of atoms held together by a surrounding ?sea? of electrons (metallic bonding)

Metalloid (semimetal) an element having both metallic and nonmetallic properties

Metallurgy the scientific study of the production of metals from their ores and the making of alloys having various useful properties

Metaphosphoric acids acids with the general formula (HPO₃)_n

Metastable nucleus a nucleus in an excited state with a life-time of at least one nanosecond (10^-9 s)

Meter (m) the SI base unit of length

Micelle a colloidal-sized particle formed in water by the association of molecules or ions each of which has a hydrophobic end and a hydrophilic end

Millimeters of mercury (mmHg) a unit of pressure also known as the torr. A unit of pressure equal to that exerted by a column of mercury 1 mm high at 0.00°C.

Mineral a naturally occurring inorganic solid substance or solid solution with definite crystalline form

Miscible fluids fluids that mix with or dissolve in each other in all proportions

Mixture a material that can be separated by physical means into two or more substances

Mn²⁺ Manganese(II) ion or manganous ion

MnO₄^- Permanganate ion

Moderator a substance that slows down neutrons in a nuclear fission reactor

Molality the moles of solute per kilogram of solvent

Molar concentration (molarity), M the moles of solute dissolved in one liter (cubic decimeter) of solution

Molar gas constant (R) the constant of proportionality relating the molar volume of a gas to T/P

Molar gas volume (V_m) the volume of one mole of gas

Molar mass the mass of one mole of substance. In grams, it is numerically equal to the formula mass in atomic mass units.

Mole (mol) the quantity of a given substance that contains as many molecules or formula units as the number of atoms in exactly 12 g of carbon-12. The amount of substance containing Avogadro?s number of molecules or formula units.

Mole fraction the fraction of moles of a component in the total moles of a mixture

Mole fraction the moles of a component substance divided by the total moles of solution

Mole percent percent, in terms of moles, of a component in a solution; obtained by multiplying mole fraction by 100

Molecular equation a chemical equation in which the reactants and products are written as if they were molecular substances, even though they may actually exist in solution as ions

Molecular formula a chemical formula that gives the exact number of different atoms of an element in a molecule

Molecular geometry the general shape of a molecule, as determined by the relative positions of the atomic nuclei

Molecular mass (MM) the sum of the atomic masses of all the atoms in a molecule

Molecular orbital theory a theory of the electronic structure of molecules in terms of molecular orbitals, which may spread over several atoms or the entire molecule

Molecular solid a solid that consists of atoms or molecules held together by intermolecular forces

Molecular substance a substance that is composed of molecules, all of which are alike

Molecularity the number of molecules on the reactant side of an elementary reaction

Molecule a definite group of atoms that are chemically bonded together?that is, tightly connected by attractive forces

Monatomic ion an ion formed from a single atom

mono- 1

Monodentate ligand a ligand that bonds to a metal atom through one atom of the ligand

Monomer the small molecules that are linked together to form a polymer

Monomer a compound used to make a polymer (and from which the polymer?s repeating unit arises)

Monoprotic acid an acid that yields one acidic hydrogen per molecule

Monosaccharides simple sugars, each containing three to nine carbon atoms, generally all but one of which bear a hydroxyl group, the remaining one being part of a carbonyl group

Net ionic equation an ionic equation from which spectator ions have been canceled

Neutralization reaction a reaction of an acid and a base that results in an ionic compound and possibly water

Neutron a particle found in the nucleus of an atom; it has a mass almost identical to that of the proton but no electric charge

Neutron activation analysis an analysis of elements in a sample based on the conversion of stable isotopes to radioactive isotopes by bombarding a sample with neutrons

NH₄⁺ Ammonium ion

Ni2+ Nickel(II) ion or nickel ion

Nickel?cadmium cell a voltaic cell consisting of an anode of cadmium and a cathode of hydrated nickel oxide (approximately NiOOH) on nickel; the electrolyte is potassium hydroxide

Nitrogen cycle the circulation of the element nitrogen in the biosphere, from nitrogen fixation to the release of free nitrogen by denitrifying bacteria

Nitrogen-fixing bacteria bacteria that can produce nitrogen compounds in the soil from atmospheric nitrogen

NO₂^- Nitrite ion

NO₃^- Nitrate ion

Noble gases (inert gases; rare gases) the Group VIIIA elements; all are gases consisting of uncombined atoms. They are relatively unreactive elements

Noble-gas core an inner-shell configuration corresponding to one of the noble gases

nona- 9

Nonelectrolyte a substance, such as sucrose, or table sugar (C₁₂H₂₂O₁₁), that dissolves in water to give a nonconducting or very poorly conducting solution

Nonmetal an element that does not exhibit the characteristics of a metal

Nonstoichiometric compound a compound whose composition varies from its idealized formula

Nuclear bombardment reaction a nuclear reaction in which a nucleus is bombarded, or struck, by another nucleus or by a nuclear particle

Nuclear equation a symbolic representation of a nuclear reaction

Nuclear fission a nuclear reaction in which a heavy nucleus splits into lighter nuclei and energy is released

Nuclear fission reactor a device that permits a controlled chain reaction of nuclear fissions

Nuclear force a strong force of attraction between nucleons that acts only at very short distances (about 10^-15 m)

Nuclear fusion a nuclear reaction in which light nuclei combine to give a stabler, heavier nucleus plus possibly several neutrons, and energy is released

Nucleic acids polynucleotides folded or coiled into specific threedimensional shapes

Nucleotides the building blocks of nucleic acids

Nucleus the atom?s central core; it has most of the atom?s mass and one or more units of positive charge

Nuclide a particular atom characterized by a definite atomic number and mass number

Nuclide symbol a symbol for a nuclide, in which the atomic number is given as a left subscript and the mass number is given as a left superscript to the symbol of the element

Number of significant figures the number of digits reported for the value of a measured or calculated quantity, indicating the precision of the value






O₂^2- Peroxide ion

octa- 8

Octahedral geometry the geometry of a molecule in which six atoms occupy the vertices of a regular octahedron (a figure with eight faces and six vertices) with the central atom at the center of the octahedron

Octet rule the tendency of atoms in molecules to have eight electrons in their valence shells (two for hydrogen atoms)

OH^- Hydroxide ion

Optical isomers (enantiomers) isomers that are nonsuperimposable mirror images of one another

Optically active having the ability to rotate the plane of light waves, either as a pure substance or in solution

Orbital diagram a diagram to show how the orbitals of a sub-shell are occupied by electrons

Ore a rock or mineral from which a metal or nonmetal can be economically produced

Organic compounds compounds that contain carbon combined with other elements, such as hydrogen, oxygen, and nitrogen

Organic compounds compounds that contain carbon combined with other elements, such as hydrogen, oxygen, and nitrogen

Osmosis the phenomenon of solvent flow through a semipermeable membrane to equalize the solute concentrations on both sides of the membrane

Osmotic pressure a colligative property of a solution equal to the pressure that, when applied to the solution, just stops osmosis

osmotic pressure equation π = MRT

Ostwald process an industrial preparation of nitrogen monoxide starting from the catalytic oxidation of ammonia to nitric oxide

Overall order of a reaction the sum of the orders of the reactant species in the rate law

Oxidation the part of an oxidation?reduction reaction in which there is a loss of electrons by a species (or an increase in the oxidation number of an atom)

Oxidation number (oxidation state) either the actual charge on an atom in a substance, if the atom exists as a monatomic ion, or a hypothetical charge assigned by simple rules

Oxidation potential the negative of the standard electrode potential

Oxidation?reduction reaction (redox reaction) "a reaction in which electrons are transferred between species or in which atoms change oxidation number"

Oxide a binary compound with oxygen in the -2 oxidation state

Oxidizing agent a species that oxidizes another species; it is itself reduced

Oxoacid an acid containing hydrogen, oxygen, and another element

Oxoacid a substance in which O atoms (and possibly other electronegative atoms) are bonded to a central atom, with one or more H atoms usually bonded to the O atoms






Pairing energy (P) the energy required to put two electrons into the same orbital

Paramagnetic substance a substance that is weakly attracted by a magnetic field; this attraction generally results from unpaired electrons

Partial pressure the pressure exerted by a particular gas in a mixture

Particle accelerator a device used to accelerate electrons, protons, and alpha particles and other ions to very high speeds

Pascal (Pa) the SI unit of pressure; 1 Pa = 1 kg/(m·s²)

Pauli exclusion principle no two electrons in an atom can have the same four quantum numbers. It follows from this that an orbital can hold no more than two electrons and can hold two only if they have different spin quantum numbers.

penta- 5

Peptide (amide) bond the C?N bond resulting from a condensation reaction between the carboxyl group of one amino acid and the amino group of a second amino acid

Percentage composition the mass percentages of each element in a compound

Percentage yield the actual yield (experimentally determined) expressed as a percentage of the theoretical yield (calculated)

Period (of the periodic table) the elements in any one horizontal row of the periodic table

Periodic law when the elements are arranged by atomic number, their physical and chemical properties vary periodically

Periodic table a tabular arrangement of elements in rows and columns, highlighting the regular repetition of properties of the elements

Peroxide a compound with oxygen in the -1 oxidation state

pH the negative of the logarithm of the molar hydrogen-ion concentration

Phase one of several different homogeneous materials present in the portion of matter under study

Phase diagram a graphical way to summarize the conditions under which the different states of a substance are stable

Phospholipid a type of lipid that contains a phosphate group. These molecules have hydrophobic and hydrophilic ends, and they aggregate to give a layer structure. The process is similar to the formation of micelles.

Phospholipid bilayer a part of a biological membrane consisting of two layers of phospholipid molecules

Photoelectric effect the ejection of electrons from the surface of a metal or other material when light shines on it

Photon particle of electromagnetic energy with energy E proportional to the observed frequency of light: E = hv

Physical adsorption adsorption in which the attraction is provided by weak intermolecular forces

Physical change a change in the form of matter but not in its chemical identity

Physical property a characteristic that can be observed for a material without changing its chemical identity

Pi (p) bond a bond that has an electron distribution above and below the bond axis

Planck’s constant (h) a physical constant with the value 6.63 x 10^-34 J·s. It is the proportionality constant relating the frequency of light to the energy of a photon.

Plasma an electrically neutral gas of ions and electrons

PO₄^3- Phosphate ion

Polar covalent bond a covalent bond in which the bonding electrons spend more time near one atom than near the other

Polyamide a polymer formed by reacting a substance containing two amine groups with a substance containing two carboxylic acid groups

Polyatomic ion an ion consisting of two or more atoms chemically bonded together and carrying a net electric charge

Polydentate ligand a ligand that can bond with two or more atoms to a metal atom

Polyester a polymer formed by reacting a substance containing two alcohol groups with a substance containing two carboxylic acid groups

Polymer a very large molecule made up of a number of smaller molecules repeatedly linked together

Polymer a chemical species of very high molecular mass that is made up from many repeating units of low molecular mass

Polymerase chain reaction (PCR) a technique used to amplify the quantity of DNA in a sample

Polynucleotide a linear polymer of nucleotide units

Polypeptide a polymer formed by the linking of many amino acids by peptide bonds

Polyphosphoric acids acids with the general formula H_n+2P_nO3_n-1 formed from linear chains of P—O bonds

Polyprotic acid an acid that yields two or more acidic hydrogens per molecule

Polyprotic acid an acid that yields two or more acidic hydrogens per molecule

Positron a particle that is similar to an electron and has the same mass but has a positive charge

Positron emission emission of a positron from an unstable nucleus

Potential difference the difference in electrical potential (electrical pressure) between two points

Potential energy the energy an object has by virtue of its position in a field of force

Precipitate an insoluble solid compound formed during a chemical reaction in solution

Precision the closeness of the set of values obtained from identical measurements of a quantity

Pressure the force exerted per unit area of surface

Primary alcohol an alcohol in which the hydroxyl group is attached to a carbon atom that is itself bonded to only one other carbon atom

Primary structure (of a protein) the order, or sequence, of the amino-acid units in the protein

Principal quantum number (n) the quantum number on which the energy of an electron in an atom principally depends; it can have any positive integer value: 1, 2, 3, . . .

Product a substance that results from a chemical reaction

Protein a biological polymer of small molecules called amino acids; a polypeptide that has a biological function

Proton a particle found in the nucleus of the atom; it has a positive charge equal in magnitude, but opposite in sign, to that of the electron and a mass 1836 times that of the electron

Pseudo-noble-gas core the noble-gas core together with (n - 1)d¹⁰ electrons






Qualitative analysis the determination of the identity of substances present in a mixture

Quantitative analysis the determination of the amount of a substance or species present in a material

Quantum (wave) mechanics the branch of physics that mathematically describes the wave properties of submicroscopic particles






Racemic mixture a mixture of equal amounts of optical isomers

Rad the dosage of radiation that deposits 1 x 10^-2 J of energy per kilogram of tissue

Radioactive decay the process in which a nucleus spontaneously disintegrates, giving off radiation

Radioactive decay constant (k) rate constant for radioactive decay

Radioactive decay series a sequence in which one radioactive nucleus decays to a second, which then decays to a third, and so on

Radioactive tracer a very small amount of radioactive isotope added to a chemical, biological, or physical system to facilitate study of the system

Radioactivity spontaneous radiation from unstable elements

Raoult’s law the partial pressure of solvent, P_A, over a solution equals the vapor pressure of the pure solvent, Po_A, times the mole fraction of the solvent, X_A, in solution: P_A = P°_AX_A

Raoult’s law equation

Rate constant a proportionality constant in the relationship between rate and concentrations

Rate law an equation that relates the rate of a reaction to the concentrations of reactants (and catalyst) raised to various powers

Rate of radioactive decay formula Rate = kN_t

Rate-determining step the slowest step in a reaction mechanism

Reactant a starting substance in a chemical reaction

Reaction intermediate a species produced during a reaction that does not appear in the net equation because it reacts in a subsequent step in the mechanism

Reaction mechanism the set of elementary reactions whose overall effect is given by the net chemical equation

Reaction order the exponent of the concentration of a given reactant species in the rate law, as determined experimentally

Reaction quotient (Q_c) an expression that has the same form as the equilibrium-constant expression but whose concentration values are not necessarily those at equilibrium

Reaction quotient (Q_c) equation

Reaction rate the increase in molar concentration of product of a reaction per unit time or the decrease in molar concentration of reactant per unit time

Reducing agent a species that reduces another species; it is itself oxidized

Reduction the part of an oxidation?reduction reaction in which there is a gain of electrons by a species (or a decrease of oxidation number of an atom)

Reference form the stablest form (physical state and allotrope) of an element under standard thermodynamic conditions

Relationship between enthalpy change and heat of reaction ΔH = q_p

Relationship between molecular mass and density of a gas equation PM_m = dRT

Rem a unit of radiation dosage used to relate various kinds of radiation in terms of biological destruction. It equals the rad times a factor for the type of radiation, called the relative biological effectiveness (RBE): rems = rads x RBE.

Resonance description a representation in which you describe the electron structure of a molecule having delocalized bonding by writing all possible electron-dot formulas

Reverse osmosis a process in which a solvent, such as water, is forced by a pressure greater than the osmotic pressure to flow through a semipermeable membrane from a concentrated solution to a more dilute one

Ribonucleic acid (RNA) a constituent of cells that is used to manufacture proteins from genetic information. It is a polymer of ribonucleotide units.

Ribosomal RNA the RNA in a ribosome

Ribosomes tiny cellular particles on which protein synthesis takes place

Roasting the process of heating a mineral in air to obtain the oxide

Root-mean-square (rms) molecular speed a type of average molecular speed, equal to the speed of a molecule having the average molecular kinetic energy. It equals , where M_m is the molar mass.

Rounding the procedure of dropping nonsignificant digits in a calculation result and adjusting the last digit reported

S₂O₃^2- Thiosulfate ion

Salt an ionic compound that is a product of a neutralization reaction

Salt bridge a tube of an electrolyte in a gel that is connected to the two half-cells of a voltaic cell; it allows the flow of ions but prevents the mixing of the different solutions that would allow direct reaction of the cell reactants

Saturated hydrocarbon a hydrocarbon that has only single bonds between carbon atoms; all carbon atoms are bonded to the maximum number of hydrogen atoms (that is, the hydrocarbon is saturated with hydrogen). A saturated hydrocarbon molecule can be cyclic or acyclic.

Saturated solution a solution that is in equilibrium with respect to a given dissolved substance

Scientific method the general process of advancing scientific knowledge through observation, the framing of laws, hypotheses, or theories, and the conducting of more experiments

Scientific notation the representation of a number in the form A x 10ⁿ, where A is a number with a single nonzero digit to the left of the decimal point and n is an integer, or whole number

Scintillation counter a device that detects nuclear radiations from flashes of light generated in a material by the radiation

Second (s) the SI base unit of time

Second law of thermodynamics the total entropy of a system and its surroundings always increases for a spontaneous process. Also, for a spontaneous process at a given temperature, the change in entropy of the system is greater than the heat divided by the absolute temperature.

Secondary alcohol an alcohol in which the hydroxyl group is attached to a carbon atom that is itself bonded to two carbon atoms

Secondary structure (of a protein) the relatively simple coiled or parallel arrangement of a protein molecule

Second-order integrated rate law

Seesaw geometry the geometry of a molecule having four atoms bonded to a central atom, in which two of these outer atoms occupy axial positions of a trigonal bipyramid and the other two occupy equatorial positions

Self-ionization (autoionization) a reaction in which two like molecules react to give ions

Shell model of the nucleus a nuclear model in which protons and neutrons exist in levels, or shells, analogous to the shell structure that exists for electrons in an atom

SI base units the SI units of measurement from which all others can be derived

SI derived unit a unit derived by combining SI base units

SI prefix a prefix used in the International System to indicate a power of 10

Sigma (s) bond a bond that has a cylindrical shape about the bond axis

Significant figures those digits in a measured number (or in the result of a calculation with measured numbers) that include all certain digits plus a final digit having some uncertainty

Silica a covalent network solid of SiO₂ in which each silicon atom is covalently bonded in tetrahedral directions to four oxygen atoms; each oxygen atom is in turn bonded to another silicon atom

Silicate a compound of silicon and oxygen (with one or more metals) that may be formally regarded as a derivative of silicic acid, H₄SiO₄ or Si(OH)₄

Silicone a polymer that contains chains or rings of Si?O with one or more of the bonding positions on each Si atom occupied by an organic group

Simple cubic unit cell a cubic unit cell in which lattice points are situated only at the corners of the unit cell

Single bond a covalent bond in which a single pair of electrons is shared by two atoms

SO₃^2- Sulfite ion

SO₄^2- Sulfate ion

Sol a colloid that consists of solid particles dispersed in a liquid

Solid the form of matter characterized by rigidity; a solid is relatively incompressible and has fixed shape and volume

Solubility the amount of a substance that dissolves in a given quantity of solvent (such as water) at a given temperature to give a saturated solution

Solubility product constant (K_sp) the equilibrium constant for the solubility equilibrium of a slightly soluble (or nearly insoluble) ionic compound

Solute in the case of a solution of a gas or solid dissolved in a liquid, the gas or solid; in other cases, the component in smaller amount

Solvay process an industrial method for obtaining sodium carbonate from sodium chloride and limestone

Solvent in a solution of a gas or solid dissolved in a liquid, the liquid; in other cases, the component in greater amount

Specific heat capacity (specific heat) the quantity of heat required to raise the temperature of one gram of a substance by one degree Celsius (or one kelvin) at constant pressure

Spectator ion an ion in an ionic equation that does not take part in the reaction

Spectrochemical series an arrangement of ligands according to the relative magnitudes of the crystal field splittings they induce in the d orbitals of a metal ion

Spin quantum number (m_s) the quantum number that refers to the two possible orientations of the spin axis of an electron; its possible values are +½ and -½.

Spontaneous fission the spontaneous decay of an unstable nucleus in which a heavy nucleus of mass number greater than 89 splits into lighter nuclei and energy is released

Spontaneous process a physical or chemical change that occurs by itself

Square planar geometry the geometry of a molecule in which a central atom is surrounded by four other atoms arranged in a square and in a plane containing the central atom

Square pyramidal geometry the geometry of a molecule in which a central atom is at the apex of a pyramid and four other atoms form the square base of the pyramid

Standard (absolute) entropy (S°) the entropy value for the standard state of a species

Standard electrode potential (Eo) the electrode potential when the concentrations of solutes are 1 M, the gas pressures are 1 atm, and the temperature has a specified value?usually 25oC

Standard enthalpy of formation (standard heat of formation), ΔH°_f the enthalpy change for the formation of one mole of a substance in its standard state from its elements in their reference forms and in their standard states

Standard free energy of formation (ΔG°_f) the free-energy change that occurs when one mole of substance is formed from its elements in their stablest states at 1 atm and at a specified temperature (usually 25°C)

Standard potential the potential of a voltaic cell operating under standard-state conditions (solute concentrations are 1 M, gas pressures are 1 atm, and the temperature has a specified value—usually 25°C)

Standard state the standard thermodynamic conditions (1 atm and usually 25°C) chosen for substances when listing or comparing thermochemical data

Standard temperature and pressure (STP) the reference conditions for gases, chosen by convention to be 0°C and 1 atm

State function a property of a system that depends only on its present state, which is determined by variables such as temperature and pressure and is independent of any previous history of the system

State function a property of a system that depends only on its present state, which is determined by variables such as temperature and pressure and is independent of any previous history of the system

Statement of the Nernst formula an equation relating the cell potential, E_cell, to its standard potential cell, , and the reaction quotient, Q. At 25°C, the equation is E_cell = - (0.0592/n)log Q.

States of matter the three forms that matter can commonly assume?solid, liquid, and gas

Steam-reforming process an industrial preparation in which steam and hydrocarbons from natural gas or petroleum react at high temperature and pressure in the presence of a catalyst to form carbon monoxide and hydrogen

Stereoisomers isomers in which the atoms are bonded to each other in the same order but that differ in the precise arrangement of the atoms in space

Stock system a system of chemical nomenclature in which the charge on a metal atom or oxidation number of an atom is denoted by a Roman numeral in parentheses following the element name

Stoichiometry the calculation of the quantities of reactants and products involved in a chemical reaction

Stratosphere the region of the atmosphere occurring at 10 to 15 km above the ground level wherein the temperature increases with increasing altitude; it lies just above the troposphere, the lower portion of the atmosphere

Strong acid an acid that ionizes completely in water; it is a strong electrolyte

Strong base a base that is present in aqueous solution entirely as ions, one of which is OH^-; it is a strong electrolyte

Strong electrolyte an electrolyte that exists in solution almost entirely as ions

Structural formula a chemical formula that shows how the atoms are bonded to one another in a molecule

Sublimation the change of a solid directly to the vapor

Substance a kind of matter that cannot be separated into other kinds of matter by any physical process

Substitution reaction a reaction in which a part of the reacting molecule is substituted for an H atom on a hydrocarbon or a hydrocarbon group

Substrate the substance whose reaction an enzyme catalyzes

Superoxide a binary compound with oxygen in the -½ oxidation state; it contains the superoxide ion, O₂^-

Supersaturated solution a solution that contains more dissolved substance than does a saturated solution; the solution is not in equilibrium with the solid substance

Surface tension the energy required to increase the surface area of a liquid by a unit amount

Surroundings everything in the vicinity of a thermodynamic system

Synthesis gas reaction a chemical reaction in which a mixture of CO and H₂ gases is used in the industrial preparation of a number of organic compounds, including methanol, CH₃OH

System (thermodynamic) the substance or mixture of substances under study in which a change occurs

Termolecular reaction an elementary reaction that involves three reactant molecules

Tertiary alcohol an alcohol in which the hydroxyl group is attached to a carbon atom that is itself bonded to three carbon atoms

Tertiary structure (of a protein) the structure associated with the way the protein coil is folded

tetra- 4

Tetrahedral geometry the geometry of a molecule in which four atoms bonded to a central atom occupy the vertices of a tetrahedron with the central atom at the center of this tetrahedron

Theoretical yield the maximum amount of product that can be obtained by a reaction from given amounts of reactants

Theory a tested explanation of basic natural phenomena

Thermal equilibrium a state in which heat does not flow between a system and its surroundings because they are both at the same temperature

Thermochemical equation the chemical equation for a reaction (including phase labels) in which the equation is given a molar interpretation, and the enthalpy of reaction for these molar amounts is written directly after the equation

Thermochemistry the study of the quantity of heat absorbed or evolved by chemical reactions

Thermodynamic equilibrium constant (K) the equilibrium constant in which the concentrations of gases are expressed in partial pressures in atmospheres, whereas the concentrations of solutes in liquid solutions are expressed in molarities

Thermodynamics the study of the relationship between heat and other forms of energy involved in a chemical or physical process

Thermodynamics the study of the relationship between heat and other forms of energy involved in a chemical or physical process

Third law of thermodynamics a substance that is perfectly crystalline at 0 K has an entropy of zero

Titration a procedure for determining the amount of substance A by adding a carefully measured volume of a solution with known concentration of B until the reaction of A and B is just complete

Transfer RNA (tRNA) a small RNA molecule; it binds to a particular amino acid, carries it to a ribosome, and then attaches itself (through base pairing) to a messenger RNA codon

Transition elements the B columns of elements in the periodic table

Transition elements the d-block transition elements in which a d subshell is being filled

Transition elements those metallic elements that have an incompletely filled d subshell or easily give rise to common ions that have incompletely filled d subshells

Transition-state theory a theory that explains the reaction resulting from the collision of two molecules in terms of an activated complex (transition state)

Transmutation the change of one element to another by bombardment of the nucleus of the element with nuclear particles or nuclei

Transuranium elements those elements with atomic numbers greater than that of uranium (Z = 92), the naturally occurring element of greatest Z

tri- 3

Trigonal bipyramidal geometry the geometry of a molecule in which five atoms bonded to a central atom occupy the vertices of a trigonal bipyramid (formed by placing two trigonal pyramids base to base) with the central atom at the center of this trigonal bipyramid

Trigonal planar geometry the geometry of a molecule in which a central atom is surrounded by three other atoms arranged in a triangle and in a plane containing the central atom

Trigonal pyramidal geometry the geometry of a molecule in which a central atom is at the apex of a pyramid and three other atoms form the triangular base of the pyramid

Triple bond a covalent bond in which three pairs of electrons are shared by two atoms

Triple point the point on a phase diagram representing the temperature and pressure at which three phases of a substance coexist in equilibrium

T-shaped geometry the geometry of a molecule in which three atoms are bonded to a central atom to form a T

Two-point form of the Clausius–Clapeyron equation

Tyndall effect the scattering of light by colloidal-size particles






Uncertainty principle a relation stating that the product of the uncertainty in position and the uncertainty in momentum (mass times speed) of a particle can be no smaller than Planck?s constant divided by 4p

Unimolecular reaction an elementary reaction that involves one reactant molecule

Unit a fixed standard of measurement

Unit cell the smallest boxlike unit (each box having faces that are parallelograms) from which you can imagine constructing a crystal by stacking the units in three dimensions

Unsaturated hydrocarbon a hydrocarbon that has at least one double or triple bond between carbon atoms; not all carbon atoms are bonded to the maximum number of hydrogen atoms (that is, the hydrocarbon is unsaturated with hydrogen)

Unsaturated solution a solution that is not in equilibrium with respect to a given dissolved substance and in which more of the substance can dissolve






Valence bond theory an approximate theory to explain the electron pair or covalent bond in terms of quantum mechanics

Valence electron an electron in an atom outside the noble-gas or pseudo-noble-gas core

Valence-shell electron-pair repulsion (VSEPR) model "predicts the shapes of molecules and ions by assuming that the valence-shell electron pairs are arranged about each atom so that electron pairs are kept as far away from one another as possible, thus minimizing electron-pair repulsions"

van der Waals equation an equation that is similar to the ideal gas law but includes two constants, a and b, to account for deviations from ideal behavior

van der Waals equation

van der Waals forces a general term for those intermolecular forces that include dipole?dipole and London forces

Vapor the gaseous state of any kind of matter that normally exists as a liquid or solid

Vapor pressure the partial pressure of the vapor over the liquid, measured at equilibrium at a given temperature

Vapor -pressure lowering equation

Vaporization the change of a solid or a liquid to the vapor

Vapor-pressure lowering a colligative property equal to the vapor pressure of the pure solvent minus the vapor pressure of the solution

Viscosity the resistance to flow that is exhibited by all liquids and gases

Volatile refers to a liquid or solid having a relatively high vapor pressure at normal temperatures

Volt (V) the SI unit of potential difference

Voltaic cell (galvanic cell) an electrochemical cell in which a spontaneous reaction generates an electric current

Volumetric analysis a method of analysis based on titration






Wavelength (λ) the distance between any two adjacent identical points of a wave

Weak acid an acid that is only partly ionized in water; it is a weak electrolyte

Weak base a base that is only partly ionized in water; it is a weak electrolyte

Weak electrolyte an electrolyte that dissolves in water to give a relatively small percentage of ions

Work the energy exchange that results when a force F moves an object through a distance d; it equals F x d






Zero-order integrated rate law

Zinc?carbon (Leclanché) dry cell a voltaic cell that has a zinc can as the anode; a graphite rod in the center, surrounded by a paste of manganese dioxide, ammonium and zinc chlorides, and carbon black, is the cathode

Zn²⁺ Zinc ion

Zwitterion an amino acid in the doubly ionized form, in which the carboxyl group has lost an H⁺ to give —COO^- and the amino group has gained an H⁺ to give —NH3⁺