Selected Chemistry Vocabulary
aqueous solution - substance dissolved in water.
balanced equation - the description of a chemical reaction that gives the chemical
formulas of the reactants and the products of the reaction, with coefficients introduced
so that the number of each type of atom and the total charge is unchanged by the
reaction. For example, a balanced equation for the reaction of sodium metal (Na(s)) with
chlorine gas (Cl2(g)) to form table salt (NaCl(s)) would be 2 Na(s) + Cl2(g) = 2 NaCl(s).
bond – an attraction between atoms brought about by a sharing of electrons between
two atoms or a complete transfer of electrons. Three types of bonds are ionic, covalent
and polar covalent.
buffer – a solution containing either a weak acid and its salt or a weak base and its salt,
which is resistant to changes in pH.
catalyst - substance that increases the rate of a chemical reaction, without being
consumed or produced by the reaction. Catalysts speed both the forward and reverse
reactions, without changing the position of equilibrium.
chemical change - a dissociation, recombination, or rearrangement of atoms.
chemical equation - a compact notation for describing a chemical change. The
formulas of the reactants are added together on the left hand side of the equation; the
formulas of the products are added together on the right side. Coefficients are inserted
before the formulas to ensure that the equation is balanced. The phase in which each
substance is found is usually indicated in parentheses after each formula. For example,
2 H2(g) + O2(g) = 2 H2O(g) indicates that 2 moles of hydrogen gas combine with one
mole of oxygen gas to produce two moles of steam.
chemistry – the scientific study of matter, its properties and the interactions with other
matter and with energy.
compound - a compound is a material formed from elements chemically combined in
definite proportions by mass. For example, water is formed from chemically bound
hydrogen and oxygen.
concentration – the amount of solute dissolved in the solvent represented as percent
composition by mass, volume percent, mole fraction, molarity, molality, or normality.
density – mass per unit volume
dilutions - whenever a solvent is added to a solution. Adding solvent results in a
solution of lower concentration.
distillation – method for separating mixtures based on differences in the conditions
required to change the phase of components of the mixture. For example: to seperate
Selected Chemistry Vocabulary
mixture of liquids, the liquid can be heated to force components, which have different
boiling points, into the gas phase.
electrolyte - a substance that dissociates fully or partially into ions when dissolved in a
solvent, producing a solution that conducts electricity.
ion – an atom or molecule which has gained or lost one or more of its valence
electrons, giving it a net positive or negative electrical charge.
indicator - a substance that undergoes a sharp, easily observable change when
conditions in its solutions change, such as acid-base indicator.
insoluble - a substance that does not dissolve in a solvent to any significant degree.
Compounds with solubilities of less than 1 g per liter of water are often referred to as
'insoluble', even though they do dissolve to a small extent.
kinetic molecular theory of matter – A model of molecular motion that is used to
explain many of the properties of gases. The theory, that attempts to explain
macroscopic observations on gases in microscopic or molecular terms.
mixture – combination of two or more components where the components do not form
chemical bonds and can be separated by physical means.
precipitate - an insoluble substance that has been formed from substances dissolved
in a solution.
product – the substance that is produced during a chemical change
reactant – the substance that is consumed during a chemical change
saturated solution - solution which does not dissolve any more solute. When a
saturated solution is placed in contact with additional solute, solute neither dissolves nor
is deposited from a saturated solution.
solubility - concentration of a substance in a saturated solution. Substances with
solubilities much less than 1 g/100 mL of solvent are usually considered insoluble.
solution - a mixture without chemical bonding between the components of the solution
and the parts can be separated by physical means, such as evaporation. In a solution,
the mixing takes place at a molecular level and the resulting mixture or solution is
completely uniform or homogenous. In a solution, the properties of each component are
retained.
solvent – the component of a solution that is present in the greatest amount; the
substance in which the solute is dissolved.
Selected Chemistry Vocabulary
standard solution – a solution of precisely known concentration.
strong acid - a strong acid is an acid that completely dissociates into hydrogen ions
and anions in solution. There are six common strong acids: HCl (hydrochloric acid), HBr
(hydrobromic acid), HI (hydroiodic acid), H2SO4 (sulfuric acid), HClO4 (perchloric acid),
and HNO3 (nitric acid).
strong base - a base that completely dissociates into ions in solution. Strong bases are
strong electrolytes. The most common strong bases are alkali metal and alkaline earth
metal hydroxides.
supersaturated solution -solution has concentration of solute that is higher than its
solubility crystal of solute dropped into a supersaturated solution grows; excess solute is
deposited out of the solution until the concentration falls to the equilibrium solubility.
theory – a theory is a well-established explanation for scientific data. Theories typically
cannot be proven, but they can become established if they are tested by several
different scientific investigators. A theory can be disproven by a single contrary result.