Intermolecular forces

Question 1

Which molecules form london forces?

Answer 1

All

Question 2

How does a london force form?

Answer 2

In a moleucle one side can be more electron dense than the other at any moment (because electrons are moving) which causes an instantaneous dipole to form. This dipole can then interact with other molecules and cause the other molecule to have a instantaneous dipole moment too. Then london forces form between partial negatives and positives of separate atoms.

Question 3

Why does Cl2 have stronger london bonds than H2?

Answer 3

Cl has more electrons, so electron cloud is larger and london forces are stronger.

Question 4

Which molecules form dipole-dipole forces?

Answer 4

Only polar molecules

Question 5

How do dipole-dipole forces form?

Answer 5

Partial negative of one molecule and partial positive of another are attracted to each other and form dipole-dipole forces.

Question 6

What are hydrogen bonds and which molecules form them?

Answer 6

Permanent dipole-dipole force between a molecule with H and another with F,O or N.

Question 7

What is the order of strength of intermolecular forces?

Answer 7

Strongest

Hydrogen
Dipole-dipole
London

Weakest

Question 8

How do intermolecular forces affect viscosity?

Answer 8

Stronger IMF like hydrogen bonds means there is more attraction between molecules so it is more viscous.

Question 9

Do branched or linear molecules form stronger IMFs? Why?

Answer 9

Linear because they can be packed closely together so london forces will be stronger.