What is the difference between an ionic bond and a covalent bond?

An ionic bond is generally between a metal and a non metal atom. It is based on electrostatic attractions of two ions formed from an atoms loss or gain of electrons. A metal e.g. Li will donate one or more of its highest energy elctrons to a non metal atom e.g. Cl. This makes the metal a positively charged ion and the non metal becomes a negatively charged ion. The bond is the electrostaic attraction between the two charged ions. A covalent bond is the sharing of electrons generally between two non metallic atoms such as x2 H atoms in H2. Rather than one of the atoms donating its electrons completely like ionic bonds, the highest energy electrons are shared between the two atoms complelting the atoms electron shell structures.