Explain giving reasons:

1. Transition metals and their compounds generally exhibit a paramagnetic behaviour.

2. The chemistry of actinoids is not so smooth as that of lanthanoids.

1. Transition metals show paramagnetic nature. This paramagnetism arises due to the presence of unpaired (n-1)d electrons. Due to the presence of unpaired electrons, transition metals show paramagnetic behaviour.

Eg. Electronic configuration of Sc is [Ar] 3d¹ 4s²

For Ti it is [Ar] 3d² 4s²

For V it is [Ar] 3d³ 4s² and so on.

2. Lanthanoids primarily show three oxidation states - +2, +3 and +4. Here, amongst these oxidation states, +3 oxidation state is the most common. As the energy difference between the 4f, 5d and 6s orbitals is quite large, lanthanoids display a limited number of oxidation states.

Actinoids also has the common oxidation state of +3. But, the energy difference between 5f, 6d, and 7s orbitals is very less. Hence, actinoids display a large number of oxidation states.