Question

when atoms complete their outer electron shell by sharing electrons, they form
covalent bonds.
hydrogen bonds.
cations.
ionic bonds.
anions.

Explanation:

Covalent bonds are formed when atoms share electrons to complete their outer - electron shells. Hydrogen bonds are intermolecular forces, cations are positively charged ions formed by losing electrons, ionic bonds are formed by the transfer of electrons, and anions are negatively charged ions formed by gaining electrons.

Answer:

covalent bonds.