Explain the formation of ionic bonds in sodium chloride and sodium oxide.

Ionic bond:

It is the bond which is formed by the transfer of electron from one atom to the atom of another element.

Both bonded atoms have very large electronegativity difference. The atom with large electronegativity value accept the electron from other with smaller value of electronegativity.

For example:

Sodium chloride is ionic compound. The electronegativity of chlorine is 3.16 and for sodium is 0.93. There is large difference is present. That's why electron from sodium is transfer to the chlorine. Sodium becomes positive and chlorine becomes negative ion. Both bonded atoms are combine together through electrostatic attraction and form ionic compound sodium chloride.

NaCl

When oxygen combine with sodium it require two electrons to complete the octet and thus two sodium atom combine with one oxygen atom by transferring their valance electrons and form ionic compound sodium oxide.

Na₂O