Ions

__**Ion:**__ is an atom or group of atoms that has acquired a net electric charge as a result of gaining or losing one or more electrons
 * __Ionic bond:__** a chemical bond formed when oppositely charged ions attract
 * __Ionic compound:__** a compound composed of ions that are present in fixed proportions and arranged in a regular, geometric structure

Some elements can achieve noble gas configuration by losing or gaining electrons.

Elements want to have a noble gas configuration, because they are the most stable, so in order to do this they must either gain or lose electrons, which results in having a net electric charge.



Examples:
 * __Ionic compounds:__**
 * Elements/groups with low EN (electronegativity) tend to form cations; elements/groups with high EN tend to form anions
 * For ionic compounds, the overall compound has to be neutral; the charges have to balance each other out
 * Table salt: NaCl = Na+ + Cl-
 * Calcium sulfate: CaSO4 = Ca2+ + (SO4)2-
 * Iron (III) oxide: Fe2O3 = 2Fe3+ + 3O2-