When we talk about the hybridization of PCl3 students should not confuse it with PCl5. PCl3 is sp3 hybridized. Let us look at how this hybridization occurs and we will also understand the molecular geometry of this compound.
| Name of the Molecule | Phosphorus Trichloride |
| Molecular Formula | PCl3 |
| Hybridization Type | sp3 |
| Bond Angle | Less than 109o |
| Geometry | Trigonal Pyramidal |
What is the Hybridization of Phosphorus Trichloride?
If we look at the molecule of PCl3 it is made up of phosphorus and chlorine molecules However, the hybridization basically occurs within the central atom which is phosphorus. Now if we look at the electronic structure in the ground state of phosphorus it will be 1s2, 2s2, 2p6, 3s2, 3p2. The valence shell in phosphorus is 5. During the excited stated one of the s electrons moves to an empty d orbital resulting in the change in electronic configuration. In excited the electronic configuration will change to 1s2, 2s2, 2p6, 3s2, 3px1, 3py1, 3pz1. Now, three unpaired electrons will be used to form bonds with 3 chlorine atoms. During the formation of the bond, four orbitals (3s2, 3px1, 3py1, 3pz1) will hybridize to form 4 equivalent sp3 hybrid orbitals. One of the hybrid orbitals will contain one lone pair of electrons.
The P-Cl bonds are basically formed when the sp3 hybrid orbitals overlap with 3p orbitals of chlorine which are singly occupied. Further, each chlorine atom also holds 3 lone pairs. All in all, if we look at PCl3, there are 3 electron pairs, 3 bond pairs and one lone pair of electrons.
Important Points To Remember
- The central atom phosphorus is involved in sp3 hybridisation with three bond pairs and one lone pair.
- In the excited stated one of the s electrons moves to an empty d orbital resulting in the change in electronic configuration.
- The P-Cl covalent bonds are formed as a result of sp3 hybrid orbitals overlapping with 3p orbitals of chlorine.
PCl3 Molecular Geometry And Bond Angles
Looking at the PCl3 molecular geometry it is trigonal pyramidal with a bond angle of approx. 103o. The is mainly due to the disproportionate influence or greater repulsion of the phosphorus lone pair which makes it deviate from the ideal angle of 109o.
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