* assuming atoms of the same element surround the central atomMolecules Can Also Be Polar or Nonpolar
We talked earlier about covalent bonds being polar or nonpolar, depending on
the electronegativity difference between the bonded atoms. Well, molecules can
also be polar or nonpolar. How can you tell if a molecule is polar or nonpolar? If
the molecule is diatomic, it’s easy: Any diatomic molecule that has a polar bond
is polar, for example, CO. Any diatomic molecule that has a nonpolar bond is
nonpolar. For example, all elemental diametric molecules, such as Cl 2 , N 2 , and
O 2 , are nonpolar. Otherwise there will be some electronegativity difference that
makes the bond, and thus the molecule, polar. Molecules that consist of three or
more atoms are generally polar unless the following condition is met: If the
central atom has no lone pairs and is surrounded by atoms of one element, then
the molecule will be nonpolar, for example, CO 2 . In these cases, the individual
bond polarities cancel each other out. So it’s possible for a molecule to contain
polar bonds but, itself, be nonpolar. Methane is an example of this.