1.28 describe the formation of ions by the gain or loss of electrons

Ionic Bonding

Atoms are neutral, because they have equal numbers of protons and electrons. Ions are charged because they have different numbers of protons and electrons.

If an atom gains electrons, it becomes a negative ion. e.g. if Br gains 1 electron in becomes Br-

If an atom loses electrons, it becomes a positive ion. e.g. if Mg loses 2 electrons it becomes Mg2+