Any and all ionic compounds are called salts. All salt particles consist of a positive ion and a negative ion, held together by the same rule that makes balloons stick to walls. Applying the logic of Bonding​ in the periodic table,

• all metals form positive ions
• The atoms of Group I: Alkali metals form ions of charge 1+ by donating a single electron.
• The atoms of Group II: Alkaline earth metals form ions of charge 2+ by donating two electrons.
• all nonmetals form negative ions
• The atoms of Group VII: Halogens form ions of charge 1− by gaining one additional electron.
• The atoms of Group VI: Oxygen​ form ions of charge 2− by gaining two additional electrons.

The key to balancing these salty reactions is to balance the charges on both ions in the compound. For example,

• Ca, calcium (kalsium) forms the ion [[$\text{Ca}^{2+}$]]
• O, oxygen (happi)​ forms the ion [[$\text{O}^{2−}$]]
• As the charges match, the formula for calcium oxide is [[$\text{CaO}$]].

However,

• Li, lithium (litium)​ forms the ion [[$\text{Li}^{1+}$]]
• S, sulfur (rikki)​ forms the ion [[$\text{S}^{2−}$]]
• As there must be twice the amount of lithium ions compared to oxide ions, the formula for lithium sulfide is [[$\text{Li}_2\text{S}$]].

Furthermore,

• Mg, magnesium​ forms the ion [[$\text{Mg}^{2+}$]]
• N, nitrogen (typpi)​ forms the ion [[$\text{N}^{3−}$]]
• To cancel the charge, the balanced formula for magnesium nitride is [[$\text{Mg}_3\text{N}_2$]].