The atomic orbitals of the central atom mix to form hybrid orbitals are one s and three p.
Pauling supposed that in the presence of four hydrogen atoms, the s and p orbitals form four equivalent combinations which he called hybrid orbitals.
Phosphorus pentafluoride has 5 regions of electron density around the central phosphorus atom (5 bonds, no lone pairs).
The resulting shape is a trigonal bipyramidal in which three fluorine atoms occupy equatorial and two occupy axial positions.
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