Which one of the following represents the correct combination of shape and hybridisation of PF₅ ?
Square pyramidal, dsp³
Trigonal bipyramidal, dsp³
Square pyramidal, sp³d
Trigonal bipyramidal, sp³d
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UPSC Geoscientist – 2024
Number of sigma bonds around P = 5.
Number of lone pairs on P = (Valence electrons on P – number of bonding electrons) / 2 = (5 – 5*1) / 2 = 0 lone pairs.
The steric number (number of sigma bonds + number of lone pairs) = 5 + 0 = 5.
A steric number of 5 corresponds to sp³d (or dsp³) hybridization. This hybridization involves one s orbital, three p orbitals, and one d orbital combining to form five hybrid orbitals.
According to VSEPR theory, when there are 5 electron groups and no lone pairs around the central atom, the electron group geometry is trigonal bipyramidal, and the molecular shape is also trigonal bipyramidal.
The five hybrid orbitals in sp³d hybridization are directed towards the vertices of a trigonal bipyramid.