Any of a subgroup of rare-earth elements, of which the cerium and terbium metals comprise the other two subgroups.
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Kinetic-molecular Theory
A theory, that attempts to explain macroscopic observations on gases in microscopic observations on gases in microscopic observations on gases in microscopic or molecular terms.
Anion
A negative ion, an atom or goup of atoms that has gained one or more electrons.
Born-Haber Cycle
A series of reactions (and accompanying enthalpy changes) which, when summed, represents the hypothetical one-step reaction by which elements in their standard states are converted into crystals of ionic compounds (and the accompanying enthalpy changes.)
Ideal Solution
A solution that obeys Raoult's Law exactly.
Photochemical Smog
A brownish smog occurring in urban areas receiving large amounts of sunlight, caused by photochemical (light-induced) reactions among nitrogen oxides, hydrocarbons and other components of polluted air that produce photochemical oxidants.
Formula Weight
The mass of one formula unit of a substance in atomic mass units.
Supercritical Fluid
A substance at temperature above its critical temperature.
xenon trioxide
A colorless, nonvolatile solid, XeO3, explosive when dry: in solution it is called xenic acid.
Molecular Orbital
An orbit resulting from overlap and mixing of atomic orbitals on different atoms. An MO belongs to the molecule as a whole.
Percent Composition
The mass percent of each element in a compound.
