Question

What is the molecular geometry of PBr5? Draw its VSEPR and Lewis structure.

Answer 1

`PBr_5`'s molecular geometry is trigonal bipyramidal.

Let's start with its Lewis structure. `P` has 5 valence electrons and `Br` has 7 valence electrons, which means that a total of `5 + 5*7 = 40` electrons must be accounted for.

`P`'s bonds with the five `Br` atoms account for `5 * 2 = 10` electrons, while the three lone pairs on each `Br` atom complete the rest of the electrons - `5 * 6 =30` electrons.

SInce `P` forms bonds with 5 other atoms and has no lone pairs, it has a steric number and a coordination number equal to 5 . According to VSEPR Theory, this corresponds to a trigonal bipyramidal molecular geometry.