Question

Why are all the p - f bonds in pf5 not of the same length?

Answer 1

Hello frnd , here is ur answer
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PF is spd hybridized and the shape of molecule is trigonal bipyramidal. Three atoms of F will occupy equatorial position with bond angle of 120 degree while other two F atom will placed at axial positionwith bond angle of 180 degree. The axial bonds are experiencing more repulsion (due to the bond angle of 90 with F atom present atequatorial position from both side because they are perpendicular to each other) than those of theequatorial and this leads to longer bonds. Bond length of axial bond is greater than equatorial bond.Therefore bond will be different w.r.t. axial and equatorial position.

Answer 2

concept :- bond length depends upon hybridization of molecule .

Hybridization of molecule PF5 :
total number of atoms = 5
no of lone pair = ( 5+ 7×5-8×5)/5 = 0
hence, hybridization of PF5 = SP³d

we know, structure of SP³d is an Triangular bipyramidal .in which three bonds have equal length but two bonds (axial bond) are longer.

Hence, all bonds aren't equal in SP³d
so, all bonds of PF5 isn't equal .