Ionic Compounds

Objective: Compare electron transfer, sharing, and delocalization.

Ionic bonding describes electrostatic attraction among oppositely charged ions, often in an extended lattice rather than isolated formula-unit molecules. Covalent bonding describes atoms sharing electron density, with bonds ranging in polarity. Metallic bonding involves mobile or delocalized electrons in a metal structure. These categories are models along a continuum of electron distribution; a bond is not fully classified solely by saying one atom is a metal. In sodium chloride, sodium and chloride ions form a crystal lattice; in a water molecule, O–H bonds share electrons unequally. Properties such as conductivity and melting behavior depend on structure as well as bond type.

Objective: Apply ionic compounds to calculations, evidence, and specified situations.

Name the cation first and then the anion. Monatomic anions commonly use the -ide ending, while polyatomic ions keep their established names. A Roman numeral specifies the charge of a variable-charge metal, not the number of atoms. Prefixes such as di- and tri- are not normally used to name simple ionic compounds. A correct name and formula must describe charges that sum to zero, and learners should use a supplied ion table rather than infer an unfamiliar polyatomic charge.