Question

The molecular geometry of a molecule describes the three-dimensional shape of just the atoms. This is in contrast to the electronic geometry, which describes the shape of all electron regions. To determine the molecular geometry of a molecule, one must first determine the electronic geometry by drawing the Lewis structure. What is the molecular geometry of PH3?

Answer 1

Answer:

trigonal pyramid

Explanation:

$PH_3$

Valence electrons of phosphorus = 5

Valence electrons of hydrogen  = 1

The total number of the valence electrons  = 5 + 3(1) = 8

The Lewis structure is drawn in such a way that the octet of each atom and duet for the hydrogen in the molecule is complete. So,  

The Lewis structure is shown below in the image below.

The central atom , P has 3 bonded pairs of electrons and 1 non bonded.

Number of bond pairs = 3

Number of lone pairs = 1

The formula is $AB_3L$.

According to VSEPR theory, $PH_3$ has trigonal pyramidal shape to minimize the repulsions.