Occurs to satisfy the rule of octet - so that all atoms involved have full valence energy levels.
Electrons are transferred - from the metal to the non-metal.
Forms two ions (cations - positively charged; anions - negatively charged) that bond via electrostatic attraction.
The overall charge of the compound must be neutral (0 charge) - the charge of the cation and the anion must balance each other out.
Subscripts (numbers to the bottom-right of each element abbreviation) are used to increase the amount of the metal and/or the non-metal to balance out the charges of the cation and anion in the compound.
When subscripts are added, it multiplies the charge of each ion.
To name a compound, the name of the metal is not changed; the last syllable of the non-metal is replaced with "ide" - unless the compound has a polyatomic ion.