2.4 Intermolecular Forces

Question 1

What is London dispersions forces?

Answer 1

Temp. forces caused by the movement of electrons in a molecule; not very strong. Can be any two molecules

Question 2

What are dipole-dipole attractions?

Answer 2

Between any two polar molecules.

Question 3

What are hydrogen bonds?

Answer 3

Between two very polar molecules that contain N-H, O-H, F-H bond.

Question 4

Rank the Intermolecular attractions from weakest to strongest.

Answer 4

London dispersion, Dipole-Dipole, then Hydrogen Bonds

Question 5

Is a water molecule polar?
(Two Hydrogens, One Oxygen structure)

Answer 5

Yes, because the electrons are being pulled to one end (Oxygen) It also contains a polar bond.

Question 6

What makes a molecule polar?

Answer 6

Must contains polar covelant bond and asymmetrical ends.

Question 7

What are asymmetrical ends?

Answer 7

The electrons pulled to one end instead of cancelling each other out.

Question 8

A molecular Oxygen (O2) is given with a EN of 3.5 for one oxygen bond.
1. Is there a stronger atom?
2. Will it be polar or nonpolar?

Answer 8

1. No,they have equal EN
2. Non-Polar, they are equal.

Question 9

Ammonia (NH3)
N has an EN of 3.0
H has an EN of 2.1
1. Which atom wins?
2. Polar or Nonpolar?

Answer 9

1. Nitrogen has higher EN, so it will have stronger pull
2. Polar, because the N end is partially negative and the H is partially positive.

Question 10

What does hydrophobic and Hydrophilic mean?

Answer 10

Hydrophobic means water-hating.
Hydrophillic means water-loving.

Question 11

How do you determine is a molecule is hydrophillic?

Answer 11

If there is an -OH group on a molecule than that region will be polar and will form bonds with water.

Question 12

How do you determine is a molecule is hydrophobic?

Answer 12

If the molecule has only C-H bonds than that region will be Nonpolar, therefore it will not forma strong attraction with the water.