Inter Molecular Forces

How They Relate to VESPR Theory

Intermolecular

Forces – forces that hold molecules together. Molecules will stick together based on what kind of internal bonding they have. Intermolecular forces are not true bonds, but they are strong enough to keep molecules from separating easily.

3

Main Types of Intermolecular Forces Dipole-Dipole Hydrogen Bonding London Dispersion

Forces

Dipole-Dipole

Forces – a dipole is formed when one end of a bond is positive while the other end is negative. The

negative end will attract the + end of another molecule (& vice versa) creating a big intermolecular force. They are short range forces. ex: HCl with HCl, NH3 with NH3

Hydrogen

“Bonding” – occurs when hydrogen is bonded to an electronegative element. (H with N, O, F) It

is a form of dipole-dipole force that is particularly strong because the bond between H & N, O, F is so polar. Hydrogen bonds are often drawn as dotted lines. EX H2O The more electronegative the element, the stronger the hydrogen bonding.

London

Dispersion Forces – weak intermolecular forces that result from electrons moving around in molecules. All

molecules have London Forces. They are stronger/more predominant in larger molecules. (more electrons))

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