Hydrogen Bonding

• Hydrogen Bonding takes place under 2 conditions:

  1. Hydrogen must be bonded to a very electronegative element - Nitrogen, Oxygen or Florine
  2. Electronegative element must have a lone pair of electrons
• Noble gases show a gradual increase in boiling point:

  This is because as there are more electrons in the atom therefore there are stronger van der Waals forces
• Boiling points of N, O, F do not follow this trend:

  This is because added to the van der Waals forces, Hydrogen bonding is present in between the atoms and this is harder to separate as more energy is required to break the Strong Hydrogen bonds
• Ice is less dense than water:

  1. This is because when water freezes, The water molecules are arranged in a structure held together by hydrogen bonds

  2. In this structure water molecules are further apart than in liquid water therefore ice is less dense and floats
• Ice insulates the water below preventing the water from completely freezing and this helps organisms grow underwater