How does hybridisation of PCL5 change when it is decomposed to PCL3 and Cl2?
To understand how the hybridization of PCl5 changes when it decomposes to PCl3 and Cl2, we need to first understand the concept of hybridization.
Hybridization is a concept used to describe the mixing of atomic orbitals to form new hybrid orbitals that are optimized for bonding. This process occurs when atoms form covalent bonds. The resulting hybrid orbitals have different shapes and energy levels compared to the original atomic orbitals.
In the case of PCl5, which stands for phosphorus pentachloride, the central phosphorus (P) atom is bonded to five chlorine (Cl) atoms. Phosphorus has an electron configuration of 1s2 2s2 2p6 3s2 3p3, meaning it has three unpaired electrons in its 3p orbitals.
When PCl5 decomposes into PCl3 and Cl2, one chlorine atom dissociates, leaving behind PCl3 and Cl2 molecules. Let's see how the hybridization changes step by step:
1. Initially, in PCl5, the phosphorus atom undergoes sp3d hybridization. This means that one 3s orbital, three 3p orbitals, and one 3d orbital combine to form five sp3d hybrid orbitals.
2. Each of these sp3d orbitals then overlaps with a chlorine 3p orbital to form five sigma (σ) bonds.
Now, when PCl5 decomposes into PCl3 and Cl2:
1. One chlorine atom dissociates from the phosphorus atom, resulting in PCl3 and Cl2 molecules.
2. In PCl3, the phosphorus atom still retains its sp3 hybridization with three chlorine atoms. This means one 3s and three 3p orbitals combine to form four sp3 hybrid orbitals.
3. Each of these sp3 orbitals in PCl3 overlaps with a chlorine 3p orbital to form three sigma (σ) bonds.
4. The remaining chlorine atom (Cl2) does not involve hybridization as it exists as a diatomic molecule. Each chlorine atom in Cl2 retains its original 3p orbitals and forms a covalent bond with another chlorine atom.
In summary, when PCl5 decomposes into PCl3 and Cl2, the hybridization of the phosphorus atom changes from sp3d in PCl5 to sp3 in PCl3.