**The Valency of Sulphur**

**Definition and Explanation:**
Valency is the combining capacity of an element or the number of electrons an atom of that element can gain, lose, or share to form chemical bonds with other atoms. It determines the number of bonds an atom can form and the type of ions it can produce.

**Valency of Sulphur:**
The valency of sulphur varies depending on the compound it forms. Sulphur can exhibit valencies of 2, 4, and 6.

1. **Valency 2:**
When sulphur forms compounds with metals or nonmetals that have a higher electronegativity, it tends to gain two electrons to achieve a stable electron configuration. For example, in compounds like hydrogen sulfide (H2S) and water (H2O), sulphur has a valency of 2. In H2S, sulphur forms a covalent bond by sharing one electron with each hydrogen atom, resulting in a stable molecule.

2. **Valency 4:**
In some compounds, sulphur can exhibit a valency of 4 by sharing four electrons with other atoms. For instance, sulphur dioxide (SO2) and carbon disulfide (CS2) are compounds where sulphur has a valency of 4. In SO2, sulphur forms a double bond with oxygen, sharing two electrons, and also shares two electrons with another oxygen atom. Similarly, in CS2, sulphur forms double bonds with two carbon atoms, sharing four electrons.

3. **Valency 6:**
Sulphur can also have a valency of 6 when it forms compounds such as sulfuric acid (H2SO4) and sulfate ions (SO4²⁻). In H2SO4, sulphur forms two double bonds with two oxygen atoms, sharing four electrons. It also shares two electrons with two hydrogen atoms. In sulfate ions, sulphur forms four double bonds with four oxygen atoms, sharing eight electrons.

**Conclusion:**
The valency of sulphur can be 2, 4, or 6 depending on the compound it forms. Understanding the valency of sulphur is crucial in predicting its chemical behavior and the nature of the bonds it forms. By gaining, losing, or sharing electrons, sulphur can achieve a stable electron configuration and form various compounds with different valencies.