Question

The shape of ${\mathrm{H}}_3{\mathrm{O}}^{+}$ is

• A. trigonal planar
• B. pyramidal
• C. angular
• D. tetrahedral

Answer 1

The correct option is B

pyramidal

Explanation for correct option:

B. Pyramidal

Step 1: Hybridization:

• “Hybridization is defined as the process of intermixing of the orbitals of slightly different energies so as to redistribute their energies, resulting in the formation of a new set of orbitals of equivalent energies and shape.”

Step 2: Shape of ${\mathrm{H}}_3{\mathrm{O}}^{+}$:

• The molecular formula of hydronium ion is ${\mathrm{H}}_3{\mathrm{O}}^{+}$.
• The hydrogen ion does not contain any electrons.
• The oxygen atom has two lone pairs of electrons in the case of a water molecule.
• Thus, a coordinate covalent bond is formed when an oxygen atom shares its lone pair. Thus, the coordinate bond is present in the hydronium ion.
• The total valence electrons on oxygen are 5 in case of ${\mathrm{H}}_3{\mathrm{O}}^{+}$ out of which 3 are bond pairs and one is participating in lone pair. Thus, the steric number is 4. Thus, the hybridization of ${\mathrm{H}}_3{\mathrm{O}}^{+}$ is ${\mathrm{sp}}^3$.
• The formation of hydronium ion takes place like this:

• Thus, as per VSEPR the shape of the Hydronium ion is trigonal pyramidal.

Explanation for incorrect options:

Hydronium ion has a pyramidal shape. Thus options A, C, and D are incorrect.

Hence, the correct option is C i.e. pyramidal.