Page 331 - Theory and Problems of BEGINNING CHEMISTRY

320 GLOSSARY

main group one of the eight groups at the left and right of the periodic table that extend up to the first or second
period.
mass a quantitative measure of the quantity of matter and energy in a body. Mass is measured by its direct
proportionality to weight and/or to inertia (the resistance to change in the body’s motion).

matter anything that has mass and occupies space.
metathesis double substitution.
meter the basic unit of length in the metric system (about 10% greater than a yard).
metric system a system of measurement based on the decimal system and designed for ease of use, in which
prefixes are used that have the same meanings no matter what unit they are used with.
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metric ton 10 g = 1000 kg = 2200 lb.
milli prefix meaning 0.001.

millimole 0.001 mol.
mixture a physical combination of elements and/or compounds.
mol abbreviation for mole.
molal unit of molality.

molality number of moles of solute per kilogram of solvent.
molar unit of molarity.
molar mass the mass of 1 mol of a substance. The molar mass is numerically equal to the formula mass, but
the dimensions are grams per mole.
molar volume the volume of 1 mol of gas at STP; 22.4 L.
molarity number of moles of solute per liter of solution.
mole 6.02 × 10 23 units: Avogadro’s number.
moles A
mole fraction the ratio of moles of a component to total number of moles in a solution: X A = .
total moles
mole ratio a ratio of moles, such as given by a chemical formula or a balanced chemical equation.

molecular formula the formula of a compound that gives the ratio of number of atoms of each element
to number of molecules of compound. The molecular formula is an integral multiple of the empirical formula.
molecular mass the formula mass of a molecular substance. The sum of the atomic masses of the atoms in a
molecule.
molecular weight molecular mass.
molecule a combination of atoms held together by covalent bonds.

monatomic consisting of one atom. (A monatomic ion contains only one atom.)
net ionic equation an equation in which spectator ions (ions that begin in solution and wind up unchanged as
the same ion in solution) are omitted.
neutralization the reaction of an acid with a base.
neutron a neutral particle in the nucleus of the atom.

noble gas configuration an octet of electrons in the outermost shell, such as the noble gases possess when they
are uncombined. A pair of electrons in the first shell if that is the only shell, such as in helium.