Van Der Waals Forces: Overview & Q&A

[Sirsh]

Hi could someone please give me a run down of these forces? I'm studying them atm but do not really understand them. also, are double and triple bonds representations of 2electrons being shared and 3 electrons being shared? also, when drawing electrondot diagrams for molecules ect. are ionics the only ones where you draw both atms by themselves? thanks a lot to whoever helps :)

 

[JJMB]

van der Waals forces:

These are very weak forces between temporary dipoles. The electrons around a molecule aren't always symmetrical. If at a particular moment, more electrons are around the left side of a molecule than the right, then the left side carries a partial negative charge and the right side carries a partial positive charge. These partial positive and negative charges will be attracted toward partial negative and positive charges on other molecules.

These forces are relatively very weak, but as the surface area between two molecules increases, the van der Waals forces increase because there is more room for interaction.

Dipole-dipole interactions are similar to van der Waals, but these forces are between permanent dipoles while van der Waals forces are between temporary dipoles. Dipole-dipole interactions are a lot stronger than van der Waals forces.

Hydrogen bonding and ionic forces are stronger than dipole-dipole, and the stronger the intermolecular forces in a substance are, the higher the boiling and melting points will be.

You seem to have the right idea about double and triple covalent bonds, and I'm not sure what you mean in your last question.