Chromophores and Absorption of Light Quiz

Conjugation and Absorption

• Compounds with sufficient conjugation absorb in the visible region.
• The length of the conjugated system generally increases the values of λmax.

Auxochrome Groups

• An auxochrome is a group that increases the intensity of color by extending the conjugation of a chromophore.
• The -OH group is not an example of an auxochrome group.

Bathochromic Groups

• Bathochromic groups shift the absorption maximum to a longer wavelength.

Energy Transitions

• ΔE = hν = hc/λ represents the energy of a transition.

Chromophores and Transitions

• Chromophores with both π and non-bonding electrons undergo n → π* and π → π* transitions.
• The role of chromophores is to determine the color of compounds by absorbing specific wavelengths of light.

Multiple Chromophore Groups

• When two or more conjugated chromophore groups are present, the absorption maximum increases.

Comparing Compounds

• 1,3-butadiene shows a lower energy transition than ethylene.
• 1,3-butadiene shows a higher absorption maximum than ethylene.

Molecular Orbitals

• In conjugated dienes, separate alkene groups form molecular orbitals that are delocalized and extended.

Test your knowledge on chromophores and their role in the absorption of light. Explore the factors affecting the wavelength and intensity of absorption in compounds containing chromophores.