Shape of ClO₃⁻

The shape of ClO₃⁻ is triangular pyramidal. This can be explained by the following points:

- ClO₃⁻ is a negatively charged ion that consists of one central chlorine atom bonded to three oxygen atoms and having one lone pair of electrons.
- To determine the shape of ClO₃⁻, we need to consider its electron pair geometry and molecular geometry.
- The electron pair geometry of ClO₃⁻ is tetrahedral as it has four electron pairs around the central atom (three bonding pairs and one lone pair).
- However, the molecular geometry of ClO₃⁻ is triangular pyramidal as the lone pair of electrons repels the bonding pairs and pushes them closer together, causing the bond angles to be less than 109.5°.
- The three oxygen atoms are arranged in a triangular planar shape around the central chlorine atom, while the lone pair of electrons occupies the fourth position, giving it a pyramidal shape.

Therefore, the correct answer is option 'A' - triangular pyramidal.

Shape of ClO₃⁻

The ClO₃⁻ ion is a polyatomic ion that consists of one central chlorine atom bonded to three oxygen atoms. The shape of the ClO₃⁻ ion is determined by the number of electron pairs around the central chlorine atom.

VSEPR Theory

The Valence Shell Electron Pair Repulsion (VSEPR) theory provides a method for predicting the shapes of molecules and polyatomic ions based on the number of electron pairs around the central atom. According to the VSEPR theory, the electron pairs around the central atom repel each other and arrange themselves in a way that minimizes this repulsion.

Steps to Determine the Shape of ClO₃⁻

To determine the shape of ClO₃⁻, we need to follow the steps of the VSEPR theory:

1. Count the number of electron pairs around the central atom.

In ClO₃⁻, the central atom is chlorine (Cl). Chlorine has 7 valence electrons, and each oxygen atom contributes 6 valence electrons. Therefore, the total number of valence electrons in ClO₃⁻ is:

7 + 3(6) + 1 = 26

There are three oxygen atoms bonded to the central chlorine atom, and each oxygen atom shares two electrons with the chlorine atom. Therefore, there are a total of 6 electron pairs around the central chlorine atom.

2. Determine the electron pair geometry.

The electron pair geometry is the arrangement of the electron pairs around the central atom, regardless of whether they are bonding or nonbonding electron pairs. In ClO₃⁻, there are six electron pairs around the central chlorine atom. Therefore, the electron pair geometry is octahedral.

3. Determine the molecular geometry.

The molecular geometry is the arrangement of the atoms in the molecule, taking into account the positions of the electron pairs. In ClO₃⁻, there are three oxygen atoms bonded to the central chlorine atom. Therefore, the molecular geometry is determined by the positions of the oxygen atoms.

The oxygen atoms are arranged in a trigonal planar shape around the central chlorine atom. However, one of the oxygen atoms also has a lone pair of electrons. The lone pair of electrons occupies more space than a bonding pair of electrons, so it exerts a greater repulsion on the other atoms. This causes the ClO₃⁻ ion to have a distorted shape, which is best described as a trigonal pyramidal shape.

Therefore, the correct answer is option A, triangular pyramidal.