Magnesium and nitrogen atoms achieve the noble gas configuration

When magnesium atoms liaise with nitrogen atoms an ionic bond occurs. This is determined by an electron exchange. Thereby the electron configuration of the noble gases neon is achieved for both elements . In the magnesium nitride for three Mg2+-ions there are two N3--ions. Thus the substance formula is Mg3N2. Since all elements of the 2nd main group deliver two electrons and nitrogen as an element of the 5th main group takes up three electrons, the general formula for the nitrides of the 2nd main group results in: (Me2+)3 (Nome3-)2 (Me= Metal, Nome= Nonmetal). Show periodic table