Question

what is a covalent bond? when a metal and a nonmetal share electrons to achieve a full valence shell when two atoms transfer electrons to achieve a full valence shell when two nonmetals share electrons to achieve a full valence shell when two metal atoms share electrons to achieve a full valence shell

Explanation:

A covalent bond is formed when two non - metals share electrons. This sharing helps both atoms achieve a full valence shell. Metals and non - metals form ionic bonds (through electron transfer), not covalent bonds. Transfer of electrons (as in option 2) is characteristic of ionic bonds. Metal - metal bonding is different from covalent bonding.

Answer:

When two nonmetals share electrons to achieve a full valence shell.