How are chemical formulas of binary ionic compounds generally written ?

The formula of binary ionic compounds is written by following some rules and these must be followed.

1. Firstly the positively charged ion, Cation is written first and then the negatively charged, Anion is written.
2. After this the corresponding number of ions are written as the subscript.

For example CaCl₂ and NaCl.

Lets see how the ionic bonds are made.

For example the bond formed in case of NaCl is a type of ionic bond.

Na → Na ⁺  + 1e^–

Here the sodium is forming a positively charged ion called the cation.

Cl + 1 e^–   → Cl ^–

Here the Chlorine is forming a negatively charged ion called the anion.

Na⁺ + Cl^–   → NaCl