ATOMIC THEORY 10- Intermolecular: Van der Waals, Dipole Dipole Attractions and Hydrogen bonding

Hydrogen bonding (Inter)

This force of attraction occurs between molecules when hydrogen is bonded to a smaller more electronegative element such as O,F or N

Why does water have a relatively high boiling point compared to molecules of similar molecular mass (e.g. H2S)?

Because more energy is required to break the hydrogen bonds between the water molecule

Why is water a liquid rather than a gas like H2S?

The intermolecular forces of attraction between H2S are relatively weaker than the hydrogen bonds in water molecules. So molecules in hydrogen sulfite are freer to move apart making H2S a gas.

Van der Waal forces (inter)

Weak intermolecular forces of attraction that exist between all states of matter - between non-polar molecules

What are Van der Waal forces caused by

Internal shift in the electrons in the molecules (at a given time the electrons being shared may be closer to one end of the molecule than the other)

What is the only intermolecular force of attraction between gaseous molecules?

Van der Waals

Dipole Dipole Interaction

Weak intermolecular forces of attraction between polar molecules (permanent dipole as molecule is constantly polar)