The number of electrons an atom would gain or lose when forming ionic bonds. It can be positive, negative or zero.

In an ionic bond, an element will have to lose or gain electrons.

Explanation:

Ionic bond, also called electrovalent bond, type of linkage formed from the electrostatic attraction between oppositely charged ions in a chemical compound. Such a bond forms when the valence (outermost) electrons of one atom are transferred permanently to another atom. The atom that loses the electrons becomes a positively charged ion (cation), while the one that gains them becomes a negatively charged ion (anion).

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The number of electrons an atom would gain or lose when forming ionic bonds cannot be zero.