How do you know if a covalent bond has formed?

Answer 1

In general, introductory chemistry, they teach you that a covalent bond is formed between two metals or a metal and a metalloid. In fact, as long as there is some difference in electronegativity of the two atoms involved in the bond, there will be some degree of covalency, even when a bond is considered to be ionic. But I'm guessing for your purpose, the answer would be a covalent bond is formed by the sharing of electrons between 2 metals or a metal and a metalloid.