http://www.ck12.org Chapter 27. Glossary
27.8 H
half-cell
One part of a voltaic cell in which either the oxidation or reduction half-reaction takes place.
half-life (t^12 )
The time required for one half of the nuclei of a radioactive nuclide to decay.
half-reaction
An equation that shows either the oxidation or the reduction reaction that occurs during a redox reaction.
halogen
An element of Group 17 (fluorine, chlorine, bromine, iodine, and astatine).
heat
Energy that is transferred from one object or substance to another because of a difference in temperature
between them.
heat capacity
The amount of heat required to raise the temperature of an object by 1°C.
heat of combustion
The heat released when one mole of a substance is completely burned.
heat of reaction
The enthalpy change for a chemical reaction.
Heisenberg Uncertainty Principle
A principle that states it is impossible to determine simultaneously both the position and the velocity of a
particle.
Henry’s law
A gas law that states that the solubility of a gas in a liquid is directly proportional to the partial pressure of the
gas above the liquid.
Hess’s law of heat summation
A law that states that if two or more thermochemical equations can be added together to give a final equation,
then the heats of reaction can also be added to give a heat of reaction for the final equation.
heterogeneous mixture
A mixture in which the composition is not uniform throughout the mixture.
homogeneous mixture
A mixture in which the composition is uniform throughout the mixture.
Hund’s rule
A rule that states that orbitals of equal energy are each occupied by one electron before any orbital is occupied
by a second electron, and that each of the single electrons must have the same spin.
hybridization
The mixing of the atomic orbitals in an atom to produce a set of hybrid orbitals.
hybrid orbitals
The atomic orbitals obtained when two or more nonequivalent orbitals from the same atom combine in
preparation for bond formation.
hydrate
A compound that has one or more water molecules bound to each formula unit.
hydration
The process of solute particles being surrounded by water molecules arranged in a specific manner.
hydration reaction
A reaction in which water is added to an alkene.
hydrocarbon