The atom
Berylium losing electrons

Berylium has two electrons in the outer energy level. It will give two electrons away.

Notice how the berylium atom gives two electrons away. The imbalance of protons and electrons now creates a charge of +2 on the atom.

Atoms with a charge are known as IONS. More precisely atoms with a positive charge are known as cations while atoms with a negative charge are known as anions. Berylium, above, forms a cation.