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Galvanic cell a device in which chemical energy from a spontaneous redox reaction is changed to electrical energy that can be used to do work
Galvanizing a process in which steel is coated with zinc to prevent corrosion
Gamma ray
a high-energy photon
Gangue the impurities (such as clay or sand) in an ore
Gay-Lussac's Law At constant temperature and pressure, the volumes of the gases involved in chemical reactions have ratios of small whole numbers
Geiger-Miller counter (Geiger counter) an instrument that measures the rate of radioactive decay based on the ions and electrons produced as a radioactive particle passes through a gas-filled chamber
Geometrical Isomers Stereoisomers in which similar groups are located either on the same side of a molecule (cis) or on opposite sides (trans)
Glass an amorphous solid obtained when silica is mixed with other compounds, heated above its melting point, and then cooled rapidly
Glass electrode an electrode for measuring pH from the potential difference that develops when it is dipped into an aqueous solution containing H+ ions
Glycosidic linkage a C-O-C bond formed between the rings of two cyclic monosaccharides by the elimination of water
Graham's law of effusion the rate of effusion of a gas is inversely proportional to the square root of the mass of its particles
Greenhouse effect a warming effect exerted by the earth's atmosphere (particularly CO2 and H2O) due to thermal energy retained by absorption of infrared radiation
Ground state the lowest possible energy state of an atom or molecule
Group (of the periodic table) a vertical column of elements having the same valence electron configuration and showing similar properties
Haber process the manufacture of ammonia from nitrogen and hydrogen, carried out at high pressure and high temperature with the aid of a catalyst
Half-cell One electrode and its accompanying solution in a voltaic cell
Half-life (of a radioactive sample) the time required for the number of nuclides in a radioactive sample to reach half of the original value
Half-life (of a reaction) the time required for a reactant to reach half of its original concentration
Half-reactions the two parts of an oxidation-reduction reaction, one representing oxidation, the other reduction
Halogen a Group 7A element
Halogenation the addition of halogen atoms to unsaturated hydrocarbons
Hard water water from natural sources that contains relatively large concentrations of calcium and magnesium ions
Heat energy transferred between two objects due to a temperature difference between them
Heat capacity the amount of energy required to raise the temperature of an object by one degree Celsius
Heat of fusion the enthalpy change that occurs to melt a solid at its melting point
Heat of hydration the enthalpy change associated with placing gaseous molecules or ions in water; the sum of the energy needed to expand the solvent and the energy released from the solvent-solute interactions
Heat of solution the enthalpy change associated with dissolving a solute in a solvent; the sum of the energies Deeded to expand both solvent and solute in a solution and the energy released from the solvent-solute interactions
Heat of vaporization the energy required to vaporize one mole of a liquid at a pressure of one atmosphere
Heating curve a plot of temperature versus time for a substance where energy is added at a constant rate
Heisenberg uncertainty principle a principle stating that there is a fundamental limitation to how precisely both the position and momentum of a particle can be known at a given time
Heme an iron complex
Hemoglobin a biomolecule composed of four myoglobinlike
units (proteins plus heme) that can bind and transport four oxygen molecules in the blood
Henderson-Hasselbalch equation an equation giving the relationship between the pH of an acid-base system and the concentrations of base and acid
Henry's Law The solubility of a gas in a liquid is proportional to the partial pressure of the gas above the liquid
Hess's law in going from a particular set of reactants to a
particular set of products, the enthalpy change is the same
whether the reaction takes place in one step or in a series of
steps; in summary, enthalpy is a state function
Heterocyclic Molecule A cyclic carbon compound containing atoms other than carbon in the ring
Heterogeneous equilibrium an equilibrium involving reactants and/or products in more than one phase
Heterogeneous Having nonuniform composition
Heterogeneous Catalyst A catalyst, often a solid, that is not present in the same phase as the reactants and products
Heterogeneous Equilibrium An equilibrium in which more than one phase is present
Hexagonal closest packed structure a structure composed of closest packed spheres with an ababab arrangement of layers; the unit cell is hexagonal
Homogeneous Having uniform composition
Homogeneous Catalyst A catalyst present in the same phase as the reactants and products
Homogeneous equilibrium an equilibrium system where all reactants and products are in the same phase
Homopolymer a polymer formed from the polymerization of only one type of monomer
Hund's Rule The lowest energy state of an atom is that in which electrons occupy different orbitals of the same energy with parallel spins to the extent possible
Hybrid Orbitals Equivalent atomic orbitals resulting from mixing different atomic orbitals of an atom The hybrid orbitals have characteristics dependent on the particular combination of atomic orbitals
Hybridization a mixing of the native orbitals on a given atom to form special atomic orbitals for bonding
Hydration the interaction between solute particles and water molecules
Hydridic Exhibiting the character of the hydride ion
Hydride a binary compound containing hydrogen The hydride ion, H-, exists in ionic hydrides The three classes of hydrides are covalent, interstitial, and ionic
Hydrocarbon a compound composed of carbon and hydrogen
Hydrogen bonding An exceptionally strong dipoledipole attraction between an F, O, or N atom and a hydrogen atom attached to a second F, O, or N atom
Hydrogenation reaction a reaction in which hydrogen is added, with a catalyst present, to a carbon-carbon multiple bond
Hydrohalic acid an aqueous solution of a hydrogen halide
Hydronium Ion The hydrated proton, H+; the conjugate acid of water
Hydrometallurgy a process for extracting metals from ores by use of aqueous chemical solutions Two steps are involved: selective leaching and selective precipitation
Hydrophilic Having an attraction to water
Hydrophobic Having no attraction to water
Hypothesis one or more assumptions put forth to explain the observed behavior of nature

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