The Nonpolar Covalent Bond
When two nonmetals share electrons equally, they are said to be nonpolar
covalent. Because this can only occur between atoms with identical
electronegativity values, this means that the only truly nonpolar covalent bonds
are those present in molecules made up of one type of atom. For example, both
oxygen atoms in O 2 have the same “pull” on electrons, which means the
electrons in the shared bond between them are shared equally, with neither atom
gaining a negative charge. Look how two oxygen atoms bond to form a molecule
of O 2 . The dots signify oxygen’s 6 valence electrons.
Now, if each atom could somehow acquire two more electrons, it would have a
stable octet. So what happens?
Each atom donates a pair of electrons, and the shared pairs are attracted to the
nuclei of both atoms. In a sense, each atom has 8 valence electrons instead of 6.
Each atom is happy. The sharing keeps the atoms together because each atom
now has a stable octet.
The Polar Covalent Bond
The two oxygen atoms that we just looked at form a bond and share their