Question

Which of the following orbitals cannot undergo hybridization amongst themselves?
(I) 3d, 4s
(II) 3d, 4d
(III) 3d, 4s, and 4p
(IV) 3s, 3p, and 4s

A) (II)
B) (II) and (III)
C) (I), (II), and (IV)
D) (II) and (IV)

Answer 1

Hybridization is the mixing up of atomic orbitals to form new hybrid orbitals with the properties of atomic orbitals that take part in the hybridization. This can take place in orbitals having almost equivalent energy.

Complete step by step solution:
The atomic orbitals are filled with electrons governed by their energy levels. The shell with lowest energy is filled first followed by the orbital with next higher energy. The order of increasing energies of the orbitals is as follows:
1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s < 5f < 6d < 7p. Following the above given order,
(I) 3d and 4s orbitals can hybridize among themselves because they have similar energy.
(II) 3d and 4d orbitals cannot hybridize because they have dissimilar energy due to the huge difference in sizes of the orbitals. 4d is much bigger in size than 3d orbitals.
(III) 3d, 4s, and 4p can hybridize to form different hybrid orbitals due to their equivalence in sizes.
(IV) 3s, 3p, and 4s cannot hybridize because there is a huge energy difference between the 3s and 3p orbitals with the 4s orbital.

Hence the correct Answer is option D.

Note:
Rules of hybridization:

1. Only orbitals of similar energy can hybridize with each other
2. Number of orbitals mixed is the number of orbitals produced.
3. Most hybrid orbitals are similar but not identical in shape. They may differ from one another in their orientation in space.
4. Hybrid orbitals can form only sigma bonds.
5. The electron waves in the hybrid orbitals tend to repel each other and they tend to be the farthest.