What forces hold molecules together?

[nukeman]

Does the strong nuclear force and the electromagnetic force plat into it at all, as in their role in holding atoms together?

 

[SteamKing]

The strong nuclear force is significant only in the nucleus of an atom. Its magnitude drops off exponentially with distance, and is essentially nil outside the nucleus. The SNF is responsible for holding the protons in a nucleus together against the force of their electrostatic repulsion due to having like charges.

http://en.wikipedia.org/wiki/Nuclear_force

Molecular bonds, whether covalent or ionic, depend on the outer shell electron arrangement of the constituent atoms of the molecule.

http://en.wikipedia.org/wiki/Covalent_bond

http://en.wikipedia.org/wiki/Ionic_bonding