Sulphur is the second element of oxygen group but it differs in properties with oxygen in following aspects: i) Sulphur is solid at room temperature but oxygen is gas. ii) H2S is gas while H2O is liquid in room temperature. iii) Sulphur show -2, +2, +4, +6 oxidation state except -1 in peroxide. iv) In most of the cases, Sulphur forms covalent compounds but oxygen form ionic compounds.
Allotropes of sulphur:
A. Crystalline sulphur
i. Rhombic sulphur
ii) Monoclinic sulphur
B. Non-crystalline or amorphous sulphur
i) Plastic sulphur
ii) Milk of sulphur
iii) Colloidal sulphur
1. Rhombic sulphur:
* Physical Properties:
1. It is bright yellow crystalline transparent solid.
2. It is insoluble in water but soluble in CS2 (Carborn disulphite).
3. It's melting point is 114oC and its boiling point is 444oC.
4. It is the most stable form of sulphur
5. It exists as S8 molecule and has octahedral shaped crystal.
2. Monoclinic Sulphur:
1. It exists above 96oC. Below this temperature it changes into rhombic sulphur. At 96oC both sulphur are stable and co-exist. Monoclinic Rhombic
2. It is deep yellow crystalline opaque solid.
3. It is insoluble in water but soluble in CS2.
4. It exists at S8 molecule and have needle shaped crystal.