Question

The shape of gaseous \[{\text{SnC}}{{\text{l}}_2}\] is:
A ) tetrahedral
B ) linear
C ) angular
D ) T-shaped

Answer 1

Hint: First determine the number of valence electrons present in the tin atom. Then determine the steric number and hybridisation. Then determine the geometry.

Complete answer:
The central tin atom has 4 valence electrons. Out of this, two electrons are present as a lone pair of electrons and two electrons are shared with two chlorine atoms to form two tin chlorine bonds. Thus, there are two bond pairs of electrons and one lone pair of electrons. The steric number is 3. The steric number of three is associated with hybridisation. Three atomic orbitals of tin (one s and two p orbitals) undergo hybridisation to form three degenerate hybrid orbitals. Here degenerate means that all the three orbitals have the same energy. Out of these three hybrid orbitals, one contains a lone pair of electrons and two contain a bond pair of electrons. The electron pair geometry is trigonal planar and the molecular geometry is bent or angular.

Hence, the correct answer is the C ) angular.

Note: Do not write B ) linear as the correct option. If you ignore the presence of lone pairs of electrons, then you will arrive at linear geometry by saying that there are only two bonds. But this is the wrong answer. A T-shaped geometry is obtained where three bonds and two lone pairs of electrons are present. A tetrahedral geometry is obtained when four bonds and zero lone pairs of electrons are present.