Question

Some compounds are colored due to HOMO-LUMO transition. We see the complimentary color to the frequency which the electron absorbs to get the high molecular orbital. But after some the electron should return to the ground state emitting the same frequency again, and, hence, after some time the compound should start appearing white since all frequencies will be present in the light reflected by it.

Or, if the electron does not return to the ground state, there must be a point where saturation occurs, that is, all the possible electrons have gone to the excited state, in which case the compound should again appear white. So why are compounds colored?

Answer 1

Compounds appear colored because they selectively absorb certain frequencies of light and reflect or transmit the complementary frequencies, resulting in the observed color.

Step-by-step explanation:

Color in compounds is determined by the absorption of light, not the reflection or transmission of light. When a compound absorbs light, the electrons in the molecule are excited to higher-energy orbitals. The color observed is the complementary color to the light that is absorbed.

Therefore, compounds appear colored because they selectively absorb certain frequencies of light and reflect or transmit the complementary frequencies, resulting in the observed color.