https://en.wikipedia.org/wiki/Conjugated_system Read the wiki article about “con
ID: 580427 • Letter: H
Question
https://en.wikipedia.org/wiki/Conjugated_system
Read the wiki article about “conjugated systems in pigments”. Describe what the relationship is between:
(a) the conjugation of double bonds seen in a pigment’s chemical structure VS the wavelength (and color) of light absorbed by the pigment
(b)the wavelength (and color) of light absorbed by the pigment VS the wavelength (and color) SEEN by the human eye!
(c) the conjugation of double bonds seen in a pigment’s chemical structure VS the color of light SEEN by the human eye
Explanation / Answer
After going through the link sent, the following observations are made for the queries:
(a) the pigment with conjugated systems of electrons, the energy gap is very small between their ground state and excited states compared to non conjugated systems. Hence the less amount of energy is required to excite the electrons and is absorbed . Therefore the pigment with more conjugation absorbs high wavelength (less energy) than less conjugated or non conjugated pigments.
(b) and (c) these two queries are interelated as conjugation is related to wavelength. As said in the link the molecules which have less conjugated systems absorb in UV range and appear colorless to the human eye. A pigment which has more conjugated bonds will absorb low energy in the visible light thus reflecting its complimentary color to the eye. For eg: if the pigment absorbs the violet color (has high energy) its complimentary yellow is reflected which captures human eye, if the pigment absorbs low energy colors such as green or blue it compliments with red or orange which the human eye captures.
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