Which parts of the molecule benzophenone are chromophores?
is it the two aromatic rings?
what types of electronic transitions are responsible for the molecule absorbing the light?
To determine which parts of the molecule benzophenone are chromophores, we need to consider its structure and identify the functional groups that can absorb light. In benzophenone, there are two aromatic (benzene) rings connected by a carbonyl (C=O) group.
In general, aromatic rings are common chromophores as they possess a delocalized π-electron system that allows for electronic transitions to occur when light is absorbed. Therefore, both aromatic rings in benzophenone can be considered chromophores.
Regarding the types of electronic transitions responsible for the molecule absorbing light, one needs to consider the energy levels of the electrons in the molecule. When light interacts with a molecule, it can promote an electron from a lower energy level (ground state) to a higher energy level (excited state). The types of electronic transitions commonly associated with absorption of light are:
1. π → π* transition: This occurs when an electron from the π-bonding orbital of the chromophore is excited to the higher energy π*-antibonding orbital. In benzophenone, such transitions may occur in both of the aromatic rings.
2. n → π* transition: This type of transition involves excitation of an electron from a non-bonding (n) orbital to the π*-antibonding orbital. In benzophenone, this can occur in the carbonyl (C=O) group.
These electronic transitions result in the absorption of specific wavelengths of light, corresponding to the energy difference between the ground state and the excited state of the molecule.