The organic molecules shown here are derivatives of benzene in which six-membered rings are 'fused' at the edges of the hexagons.

(e) Benzene, naphthalene, and anthracene are colorless, but tetracene is orange. What does this imply about the relative HOMO–LUMO energy gaps in these molecules? See the 'Chemistry Put to Work' box on orbitals and energy.

Video transcript

Hi everyone. So here we have two structures below and therefore not to lean. Been in three in Christ scene and these are all derivatives of benzene, naphthalene and anthropocene. Our color with solids, Christine is a golden yellow. Personal solid, you asked what can be inferred about the home? A limo gap in these molecules, colored compounds absorb visible light while colorless compounds do not absorb visible light. So since Christine has a color, it's gonna absorb visible light. since Matalin and Senate three are colorless, they do not absorb visible light and instead they're gonna absorb UV. If you look at the electromagnetic spectrum going towards the right, the wavelength increases and the energy decreases since the visible light is further right than the UV on the spectrum. I see he's gonna have a longer wavelength in a smaller home a limo. Yeah. Also the absorption wavelength increases with the degree of conjugation since christ scene as the most alternating single and double bonds, It is the most conjugated. So it's gonna absorb the highest wavelength Christine as a smaller ho mo little mo energy gap and absorb visible light because it is highly conjugated. Thanks for watching my video and I hope it was helpful