Valency - The valency of an element is the number of electrons its atoms lose, gain, or share, to form a compound.

How to write formula of ionic compounds - 1. Write symbols of elements.
2. Write the valencies of each element
3. Interchange the valencies

Word equations - Show the reactant and products of a chemical reaction using their full chemical names. They reach with each other to form new substances. Conversion of reactants to products.

The Diatomic Molecules - Hydrogen, Nitrogen, Fluorine, Oxygen, Iodine, Chlorine, Bromine (Have no fear of ice cold beer)