[Unit 3.5] | Forces Between Molecules

Question 1

What are the 3 main intermolecular forces?

Answer 1

• Van Der Waal’s Forces (Weakest)
• Dipole-Dipole Forces
• Hydrogen Bonding (Strongest)

Question 2

What is the Van Der Waal’s Force?

Answer 2

It is the name given collectively to the weak electrostatic attractions caused by the protons and electrons within ALL atoms.

Question 3

What is a Dipole-Dipole Force?

Answer 3

• A force that exists between molecules that have permanent dipoles: the negative pole of one molecule will be attracted to fhe positive pole of another.

Question 4

What is a dipole moment?

Answer 4

A summary of the polarity of bonds in a molecule. It is strongly dependant on the shape of a molecule.

Question 5

What is Hydrogen Bonding?

Answer 5

It is an IMF which consists of a hydrogen atom sandwiched between two very electronegative atoms. (N,O,F)

• Example: N-H [- - -] N
( [- - -] is the hydrogen bond between two separate molecules.)

• The electronegative atom covalently bonded to the Hydrogen atom must have a lone pair.

Question 6

Why is ice less dense than water?

Answer 6

• Hydrogen bonding.