Page 332 - Theory and Problems of BEGINNING CHEMISTRY

GLOSSARY 321

normal unit of normality.

normality the number of equivalents of solute per liter of solution.
nuclear energy energy from reactions of nuclei.
nuclear reaction a reaction in which at least one nucleus undergoes change.
nucleus the tiny center of an atom containing the protons and neutrons.

octet a set of eight electrons in the outermost shell.
octet rule a generalization that atoms tend to form chemical bonds to get eight electrons in their outermost
shells or that eight electrons in the outermost shell of an atom is a stable state.
orbit the circular path of an electron about the nucleus in the Bohr theory.
orbital a subdivision of an energy level in which an electron will have a given value for each of n, l, and m l .

organic chemistry chemistry of compounds with C C and/or C H bonds.
outermost shell the largest shell containing electrons in an atom or ion.
overall equation an equation with complete compounds present, as opposed to a net ionic equation.
oxidation raising of oxidation number, by loss of (control of) electrons.
oxidation number the number of outermost electrons of a free atom minus the number of electrons the atom
“controls” in a compound, ion, or molecule.
oxidation number change method a method for balancing redox equations by balancing changes in oxidation
numbers first.
oxidation state oxidation number.
oxidizing agent reactant that causes an increase in the oxidation number of another reactant.
oxy- prefix meaning combined oxygen, as in oxyvanadium(IV) ion: VO .
2+
oxyanion a negative ion containing oxygen as well as another element, for example, NO 3− .

paraffin a saturated hydrocarbon.
parent nucleus a nucleus that disintegrates spontaneously yielding a small particle plus another nucleus of
size approximately equal to itself.

partial pressure the pressure of a component of a gas mixture.
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pascal the SI unit of pressure. (1.000 atm = 1.013 × 10 Pa = 101.3 kPa)
Pauli exclusion principle no two electrons in a given atom can have the same set of four quantum numbers.
per (1) divided by. For example, the number of miles per hour is calculated by dividing the total number of
miles by the total number of hours. (2) prefix meaning “more oxygen.”
percent composition the number of grams of each element in a compound per 100 g of the compound.
actual yield
percent yield 100 times the actual yield divided by the calculated yield: 100 × .
calculated yield
percentage the number of units of an item present per 100 units total. For example, 73 g of sand in 100 g of a
mixture (or 7.3 g in 10.0 g mixture, or 730 g in 1000 g mixture) is 73% sand.
period a horizontal array of elements in the periodic table.
periodic table a tabulation of the elements according to atomic number with elements having similar properties
in the same (vertical) group.