Phosphorus and its Valencies

Phosphorus is an element that belongs to the nitrogen family or group 15 of the periodic table. It is a non-metal and is known for its various chemical properties, including its ability to exhibit multiple valencies. Valency is the combining capacity of an atom or an element to form chemical bonds with other atoms. Phosphorus has two valencies - 3 and 5.

Valency of Phosphorus

Valency 3:
Phosphorus has a valency of 3 when it forms compounds with elements like oxygen, chlorine, and fluorine. In these compounds, phosphorus donates three electrons to form three covalent bonds with the other elements. This valency is also known as its lower valency or trivalent state.

Valency 5:
Phosphorus can also exhibit a valency of 5 when it forms compounds with elements like oxygen, chlorine, and fluorine. In this valency state, phosphorus accepts three electrons from other elements to complete its octet. This valency is also known as its higher valency or pentavalent state.

Reasons for Multiple Valencies

The multiple valencies of phosphorus can be explained by its electronic configuration and the concept of hybridization. Phosphorus has 15 electrons distributed in its electronic shells as follows:

1s2 2s2 2p6 3s2 3p3

In its ground state, phosphorus has three unpaired electrons in its 3p orbital, which are available for bonding. These electrons can be used to form three covalent bonds, resulting in the trivalent valency of phosphorus.

However, phosphorus can also undergo a process called hybridization to promote one of its 3s electrons to the 3d orbital. This results in the formation of five hybrid orbitals, each containing one electron. These five orbitals can then form five covalent bonds, giving rise to the pentavalent valency of phosphorus.

Conclusion

In conclusion, phosphorus exhibits two valencies - 3 and 5. Its valency depends on the number of electrons it donates or accepts during chemical bonding. The trivalent valency arises from the use of three unpaired electrons in its 3p orbital, while the pentavalent valency is achieved through hybridization, which forms five hybrid orbitals. Understanding the valencies of phosphorus is essential in predicting and explaining its chemical behavior and the formation of various compounds.