Question

How zno is covalent compound? provide the general rule when metal and nonmetal form covalent

Answer 1

Dear Student,

ZnO is neither purely ionic nor purely covalent. It lies on the borderline between ionic and covalent solids. Zn is a transition metal, and therefore forms ionic oxide with O^2-.
However, due to strong polarising power of the oxide ion, the Zn^​2+ ion gets polarised, and covalent character is induced in the compound. Hence, ZnO becomes partly covalent.

Whether a metal or non metal will form a covalent compound can be predicted according to Pauling scale of electronegativity or Fajan's rule.