A chemist has synthesized two new dyes based on the molecular structure of plant-based dyes. The lowest energy absorption line f
or the first dye is light in the visible region at 530 nm. The lowest energy absorption line for the second dye is light in the visible region at 645 nm. Based on this evidence, which molecule has the larger HOMO-LUMO gap? 1. The dye that absorbs at 530 nm
2. There is not enough information given to predict
3. The gap is the same, because they both absorb in visible region
4. The dye that absorbs at 645 nm
With a larger HOMO-LUMO gap, there's also a higher absorption energy, so this means that the dye with the higher absortion energy has the larger HOMO-LUMO gap.
The relationship between energy and wavelenght can be expressed by the formula E = hc/λ, this means that the <em>lower</em> the wavelenght, the <em>higher</em> the energy is. So the dye that absorbs at a lower wavelenght has a larger HOMO-LUMO gap.
When the electron changes levels, it decreases energy and the atom emits photons. The photon is emitted with the electron moving from a higher energy level to a lower energy level. The energy of the photon is the exact energy that is lost by the electron moving to its lower energy level.
