Covalent Bonds


A covalent bond normally forms between:

1.  a nonmetal and a nonmetal

2.  a nonmetal and a metalloid

3.  a metalloid and a metalloid


In polyatomic ions that contain metals and in a few other instances, covalent bonds can form between metals and nonmetals.  However, a binary compound containing a metal and and a nonmetal is always ionic.