2f sulphur and nitrogen. allotropes of sulphur sulphur molecule consists of 8 atoms in a ring form

2f Sulphur and Nitrogen

Allotropes of sulphur

Sulphur molecule consists of 8 atoms in a ring form.

Allotropes of sulphur

It melts at 115°C (low) which is because of its simple molecular structure.

Allotropes of sulphur

At first the sulphur is very runny because of the weak bonds between the sulphur molecules (intramolecular bonds)

Allotropes of sulphur

As it is heated more strongly, the rings break and join together to make long chains. It becomes sticky.

Allotropes of sulphur

Near to the boiling point, the chains start to break, the liquid is less viscous and it starts to evaporate.

Allotropes of sulphur

When it evaporates it forms S2 molecules (like O2 which is also group 6)

Allotropes of sulphur

If it is poured quickly into water, plastic sulphur is made.It is “frozen” in long chain molecules like rubber.

Allotropes of sulphur

It will eventually change back into S8.

Nitrogen

• Extracted from air by fractional distillation

• If air is cooled down, at -183°C oxygen condenses into a liquid and then at -196°C Nitrogen condenses too.

Nitrogen

Nitrogen is generally an unreactive gas, and needs fairly extreme conditions to get it to react with oxygen

Its inert nature is used to help preserve food.

Ammonia NH3

Ammonia NH3

Ammonia NH3

• Only common alkaline gas Only common alkaline gas.

• EASILY dissolves in water

• Turns damp litmus paper blue.

Laboratory preparation of NH3

• Heat solid ammonium chloride with solid calcium hydroxide

Ammonia + acids

• Ammonia (an alkali) reats with acids to form salts

NH3 + HNO3 NH4NO3

Ammonium (NH4+) salts

• Ammonium nitrate – NH4NO3

• Ammonium sulphate – (NH4)2SO4

• Ammonium chloride – NH4Cl