Module 2 Chapter 5 Lesson 4 - Intermolecular Forces

Question 1

What are the three types of intermolecular forces?

Answer 1

Hydrogen bonds
Permanent Dipole-Dipole
London Dispersion Forces (AKA Induced dipole-dipole)

Question 2

What is the strongest relative intermolecular force?

Answer 2

Hydrogen bonds

Question 3

When does hydrogen bonding occur?

Answer 3

Between hydrogen and N/O/F

Question 4

What is a feature of hydrogen bonding?

Answer 4

Very electronegative

Question 5

What is the medium strength relative intermolecular force?

Answer 5

Permanent dipole-dipole interactions

Question 6

Where are permanent dipole-dipole interactions present?

Answer 6

Polar molecules

Question 7

Define permanent dipole-dipole interactions.

Answer 7

Permanent partial charges attracting each other.

Question 8

What is the weakest relative intermolecular force?

Answer 8

London Dispersion Forces (Induced dipole-dipole forces)

Question 9

What influences the strength of London Dispersion Forces?

Answer 9

Number of electrons

Question 10

Where are LDF present?

Answer 10

All molecules

Question 11

What happens when a combination of ethanol and water is left overnight?

Answer 11

Hydrogen bonding increases.
So the atoms are closer together.
Causing the volume to decrease.

Question 12

What are the steps to find out if a molecule is polar or not?

Answer 12

Dot and Cross
3D structure
Identify lone pairs
Identify difference in dipoles
Identify bonding pairs.

Question 13

What are eight features to find out if a molecule is polar or not?

Answer 13

Lone Pairs = Polar
Difference in dipoles = Polar
Different bonding pairs = Polar
Dipoles don’t cancel out = Polar
Non - Symmetrical = Polar

Dipoles cancel out = Non - Polar
Same bonding pairs = Non - Polar
Symmetrical = Non - Polar

Question 14

What are the rules for drawing hydrogen bonding diagrams?

Answer 14

Dipoles
Dashed line for forces between molecules
Straight line for intramolecular forces

Question 15

What does electrons oscillating randomly cause?

Answer 15

Electrons oscillate and randomly move.
Uneven distribution of charge.
Creates instantaneous dipole.
Induces dipole in neighbouring molecules.

Question 16

What has stronger LDF forces Cl-Cl or Br-Br and why?

Answer 16

Br-Br
Larger/Higher molecular mass
More electrons
High uneven distribution of electrons
Higher LDF.