(9) Radicals.—A radical is an atom or group of atoms which changes places in a reaction. A compound radical is made up of different sorts of radicals, as NH4.
A basic radical is a metal, or a compound radical which behaves like a metal, e.g., Zn and NH4.
(10) Hydrates.—A hydrate is a substance formed from water by replacing half of its hydrogen by a radical, e.g., H2O + 2Na = 2NaOH + H2, where the sodium has taken the place of one atom of hydrogen.
(11) Base.—If a hydrate is formed by a basic radical, the hydrate is called a base, e.g., ZnO2H2.
(12) Alkali.—An alkali is a soluble base, e.g., NaOH, KOH, NH4OH, LiOH.
(13) Acid.—An acid is a substance containing hydrogen which may be replaced by a basic radical, e.g., 2HCl + Zn = ZnCl2 + H2.
(14) Salts.—A salt is a substance formed from an acid replacing its hydrogen by a basic radical, e.g. 2HCl + Zn = ZnCl2 + H2.
An acid salt is a compound derived from an acid which has not all of its hydrogen replaced, e.g., 2NaCl + H2SO4 = NaHSO4 + HCl + NaCl.
(15) Chemical Nomenclature.—Termination “—UM” is now applied to all Metals, though the older-known metals retain the former names, e.g.—Aluminium, Tellurium, etc.
Termination “—IDE” denotes a Binary Compound, that is, a substance composed of only two elements, e.g., Sodium Chloride (NaCl).