Hydrogen bonding

Question 1

What is a hydrogen bond?

Answer 1

A special type of permanent dipole - dipole interaction found between molecules containing:
- an electronegative atom with a lone pair of electrons, for example oxygen, nitrogen or flourine
- A hydrogen atom attached to an electronegative atom: H-O, H-N, H-F

Question 2

Draw a hydrogen bond between two molecules of water

Question 3

What are the anomalous properties of water?

Answer 3

• Ice is less dense than water
  -A relatively high melting and boiling point

Question 4

Why is ice less dense then water?

Answer 4

• Hydrogen bonds hold water molecules apart in an open lattice structure
• The water molecules in ice are further apart in water
• Therefore, solid ice is less dense than water

Question 5

Why does water have a relatively high melting or boiling point?

Answer 5

• water has london forces and hydrogen bonds
• This means more energy is required to overcome the hydrogen bonds, increasing the boiling point and melting point of water