Question

Explain giving reasons:
The transition metals generally form coloured compounds.

Answer 1

Colour of transistion metal - compounds is due to the excitation of an electron from a lower energy d-orbital to a higher energy $d$ orbital. The energy of excitation corresponds to the frequency of light absorbed and the colour observed corresponds to the complementary color of the light absorbed (whose frequency lies on the visible region).

The frequency of the light absorbed depends on the nature of the ligand. Transition metals form colored compounds due to the presence of vacant d-orbitals from the d-d transition of $electrons$ which causes the color.