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Difficulty: MediumMolecular Shapes, VSEPR Theory, and Hybridization

Complete the following statement regarding the electronic structure, hybridization, and molecular geometry of phosphorus trichloride (PCl3PCl_3).

Answer:In a molecule of phosphorus trichloride (PCl3PCl_3), the central phosphorus atom undergoes 【sp3】 hybridization and exhibits a 【trigonal pyramidal】 molecular geometry.

Answer

The central phosphorus atom in PCl3PCl_3 undergoes sp3sp^3 hybridization and adopts a trigonal pyramidal molecular geometry.
The central phosphorus atom in PCl3PCl_3 has 5 valence electrons. It uses 3 valence electrons to form single covalent bonds with three chlorine atoms, leaving 2 non-bonding valence electrons as a single lone pair. The total steric number is 4 (3 bonding pairs + 1 lone pair), which corresponds to sp3sp^3 hybridization. According to VSEPR theory, four electron pairs arrange tetrahedrally, but the presence of three bonded atoms and one lone pair produces a trigonal pyramidal molecular shape.

Step-by-Step Solution

1
Determine the valence electron count and steric number for the central atom.
Phosphorus (Group 15) has 5 valence electrons. It forms 3 single covalent bonds with chlorine atoms and retains 1 lone pair of electrons. Steric number = 3 bonding pairs + 1 lone pair = 4.
The steric number dictates the set of hybridized orbitals used by the central atom.
2
Determine the hybridization of the central atom.
A steric number of 4 corresponds to sp3sp^3 hybridization.
Four electron domains require four degenerate hybridized orbitals formed from one s orbital and three p orbitals.
3
Differentiate between electron pair geometry and molecular geometry.
The electron pair geometry is tetrahedral, but because one position is occupied by a non-bonding lone pair, the molecular geometry is trigonal pyramidal.
VSEPR theory specifies that molecular geometry considers only the spatial arrangement of the atomic nuclei.

Key Concept

VSEPR Theory, Steric Number, and Hybridization
Estimated Time:1m 0s
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Topics

Molecular Shapes, VSEPR Theory, and Hybridization

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