Study Guides/Chemistry/PCL5 Hybridization
Study Guide · Chemistry

Hybridization and Shape of PCl5

In Class 11 Chemistry (Chemical Bonding), calculating the hybridization of central atoms is a key concept. Let's determine the hybridization and molecular geometry of Phosphorus Pentachloride (PCl₅).

Question (Click to Flip)

What is the hybridization of PCl5?

Answer

The hybridization of the central phosphorus atom in PCl5 is sp3d, because it forms 5 sigma bonds with 5 chlorine atoms and has zero lone pairs.

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Key Facts

Central Atom: Phosphorus (P).

Hybridization: sp³d.

Lone Pairs: Zero.

Shape: Trigonal Bipyramidal.

Bond Angles: 120° (equatorial) and 90° (axial).

Calculating the Hybridization

To find the hybridization, we analyze the central atom, Phosphorus (P).

  • Phosphorus is in Group 15 and has 5 valence electrons in its outermost shell.
  • It forms 5 single covalent bonds with 5 Chlorine (Cl) atoms. This uses up all 5 of its valence electrons.
  • Therefore, there are 0 lone pairs remaining on the Phosphorus atom.

Steric Number = (Number of bonded atoms) + (Number of lone pairs) Steric Number = 5 + 0 = 5.

A steric number of 5 corresponds to sp³d Hybridization. (One s-orbital, three p-orbitals, and one d-orbital mix together).

Molecular Geometry (Shape)

Because there are no lone pairs to distort the shape, PCl₅ adopts a perfect Trigonal Bipyramidal geometry.

  • Three chlorine atoms lie in a flat, central triangular plane (Equatorial bonds) with angles of 120°.
  • Two chlorine atoms sit directly above and below this plane (Axial bonds) making an angle of 90° with the equatorial plane.

Note: The axial bonds in PCl₅ are slightly longer and weaker than the equatorial bonds due to greater electron repulsion.

Questions and Answers

What is the hybridization of PCl5?+

The hybridization of the central phosphorus atom in PCl5 is sp3d, because it forms 5 sigma bonds with 5 chlorine atoms and has zero lone pairs.

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