Help recognising intermolecular forces

Hi guys, I'm doing a question where it asks to identify the forces of different examples, for example:

NH3, CH4, HCl

I know Hydrogen bonds are H with N, O or F so NH3 is a hydrogen bond.

In the answer sheet it says CH4 is a van der waal bond and that HCl is a dipole dipole. How did they identify these? Is there some rule about which elements are with van der waals/dipole dipole?

Thanks

Reply 1

lordaxil

Generally, all molecules will interact via van der Waals forces, but these are less important than hydrogen bonding or dipole-dipole interactions if present. So, if as molecule has H with N, O or F then it's hydrogen bonding, or if it has atoms with very different electronegativities (like HCl) it will be dipole-dipole, otherwise van der Waals (like CH4).