Question

Explain the non-linear shape of \[\ce{H2S}\] and non-planar shape of \[\ce{PCl3}\] using valence shell electron pair repulsion theory.

Answer 1

The Lewis structure of \[\ce{H2S}\] is:

S-tom is surrounded by four electron pairs (two bonded and two lone pairs). These four electron pairs adopt tetrahedral arrangement. The presence of two lone pairs brings distortion in the molecule on account of repulsion with bonded pairs of electrons. Thus, the shape of \[\ce{H2S}\] molecule is V-shaped and not linear.

The Lewis structure of \[\ce{PCl3}\] is:

\[\begin{array}{cc}
\ce{Cl - \overset{\bullet\bullet}{P} - Cl}\\
|\phantom{.}\\
\ce{Cl}\phantom{}
\end{array}\]

P-tom is surrounded by four electron pairs (3 bonded and one lone pair). These four pairs adopt a tetrahedral geometry. Due to the presence of lone pair, \[\ce{PCl3}\] has a distorted tetrahedral geometry. Thus, it is pyramidal in shape and not non-planar shape.