Covalent bonds form between nonmetals, the electronegativity of each atom determines what type of covalent bond (polar or nonpolar) is formed.
Covalent bonds form betweenthe electrons in the outer valence of an atom. Read more: http://wiki.answers.com/Q/What_do_covalent_bonds_usually_form_between#ixzz1P5bt2UqB
Covalent compounds form when two atoms sharea pair of electrons.
No. A covalent bond will generally form between two nonmetals.
Many do. For example oxygen (O2), hydrogen (H2), etc.