Question

In which of the following bond angles is maximum?
(A) $N{{H}_{3}}$
(B) $N{{H}_{4}}^{+}$
(C) $PC{{l}_{3}}$
(D) $SC{{l}_{2}}$

Answer 1

Even though compounds have similar molecular geometry, there are a number of reasons which state that their bond angles might be different. This can be predicted manually but the actual bond angle can only be calculated by using spectroscopic methods.

Complete step by step answer:
- In order to find the bond angle, first, we have to find its geometry and hence its hybridization.
You might be thinking about what hybridization and geometry mean. Let's talk about them.
Hybridization is an idea that atomic orbitals fuse with each other to form new orbitals known as hybridized orbitals which influences their molecular geometry, atomic bonding properties and are also symmetrically disposed in space. Hybridization is also an expansion of the VBT known as valence bond theory.
Molecular geometry can be defined as a three-dimensional arrangement of atoms that constitute a molecule. It includes the general shape of a molecule as well as its bond length, bond angles, and any other geometrical parameters that determine the position of each atom.
Molecules are most often held together with covalent bonds in form of single, double, or triple bonds where the term bond is nothing but a shared pair of electrons. Molecular geometries are specified in terms of bond angles and bond lengths. The bond length is defined as the average distance between the nuclei of two atoms bonded with each other. A bond angle is an angle formed between three atoms with at least two bonds.
By the concept of VSEPR, the geometry and approximate angle of the given molecules are as follows:
- $N{{H}_{3}}$ : It has a trigonal pyramidal geometry with a single lone pair. Thus, its bond angle is approximately 106 degrees.
- The structure of the ammonia molecule is as follows.

- $N{{H}_{4}}^{+}$ : It has a tetrahedral geometry with no lone pairs. Due to the absence of lone pairs, the repulsion is much lesser compared to compounds with lone pairs. So it has an approximate bond angle of 110 degrees.
- The structure of the ammonium molecule is as follows.

- $PC{{l}_{3}}$ : It has a trigonal pyramidal geometry with one lone pair and has an approximate bond angle of 107 degrees.
- The structure of the $PC{{l}_{3}}$ molecule is as follows.

- $SC{{l}_{2}}$ : Its structure is bent and it contains two lone pairs. Therefore, it has an approximate bond angle of 109 degrees.
- The structure of the $SC{{l}_{2}}$ molecule is as follows.

So, the correct answer is “Option B”.

Note: You must remember the trend of repulsion between electron pairs in a compound in order to make a better decision about their bond angle and bond length. The trend of repulsion is as follows: Lone Pair- lone pair > Lone Pair- bond- pair > Bond Pair- bond pair.