Glossary
absolute temperature Temperature measured on the absolute scale, which has its
origin at absolute zero. See also Kelvin scale.
absorption The process of taking up by capillary, osmotic, chemical, or solvent
action, as a sponge absorbs water.
acid A water solution that has an excess of hydrogen ions; an acid turns litmus
paper pink or red, has a sour taste, and neutralizes bases to form salts.
acidic anhydride A nonmetallic oxide that, when placed in water, reacts to form
an acid solution.
acid salt A salt formed by replacing part of the hydrogen ions of a dibasic or
tribasic acid with metallic ions. Examples: NaHSO 4 , NaH 2 PO 4.
actinide series The series of radioactive elements starting with actinium, No. 89,
and ending with lawrencium, No. 103.
activated charcoal A specially treated and finely divided form of carbon, which
possesses a high degree of adsorption.
activation energy The minimum energy necessary to start a reaction.
adsorption The adhesion (in an extremely thin layer) of the molecules of gases, of
dissolved substances, or of liquids to the surfaces of solid or liquid bodies
with which they come into contact.
alcohol An organic hydroxyl compound formed by replacing one or more
hydrogen atoms of a hydrocarbon with an equal number of hydroxyl (OH)
groups.
aldehyde An organic compound formed by dehydrating oxidized alcohol; contains
the characteristic –CHO group.
alkali Usually, a strong base, such as sodium hydroxide or potassium hydroxide.
alkaline Referring to any substance that has basic properties.
alkyl A substitutent obtained from a saturated hydrocarbon by removing one
hydrogen atom.
Examples: methyl (CH 3 −), ethyl (C 2 H 5 −).
allotropic forms Forms of the same element that differ in their crystalline
structures.
alloy A substance composed of two or more metals, which are intimately mixed;
usually made by melting the metals together.
alpha particles Positively charged helium nuclei.
amine A compound such as CH 3 NH 2 , derived from ammonia by substituting one