Would the #PF_2^+# molecule be trigonal planar or bent?

1 Answer
May 18, 2017

Answer:

Well, how many valence electrons has we got? And I think you are right.

Explanation:

There are #5(P)+2xx7(F)-1=19-1=18# #"electrons"#, which we distribute around 3 centres; i.e. 9 electron pairs........

And I make this: #F-ddotP^(+)-F#.

There are 3 regions of electron density around the central phosphorus atom: the two #P-F# bonds; and the lone pair. Electronic geometry is predicted to be trigonal planar; #/_F-P-F>120^@#, due to the disproportionate influence of the #P# lone pair.

Either your teacher got it wrong, or we have misinterpreted the problem. Both scenarios are possible.