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How is benzene colourless please help

Hi guys, so I found this from my book:
"In a delocalised system like benzene- many molecular orbitals are formed. These orbitals are even closer in energy than in a double bond. The electrons in them absorb very low frequency UV and visible light when they become excited."

So I feel like this doesn't make sense because benzene is colourless so it should absorb in the UV range, and transmit all wavelengths of visible light(I think) and reflect the complementary wavelength to which it absorbed which lies in the Uv range?

Could someoen please kindly help me here?? Would really appreciate
Reply 1
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Reply 2
Original post by sienna2266
Hi guys, so I found this from my book:
"In a delocalised system like benzene- many molecular orbitals are formed. These orbitals are even closer in energy than in a double bond. The electrons in them absorb very low frequency UV and visible light when they become excited."

So I feel like this doesn't make sense because benzene is colourless so it should absorb in the UV range, and transmit all wavelengths of visible light(I think) and reflect the complementary wavelength to which it absorbed which lies in the Uv range?

Could someoen please kindly help me here?? Would really appreciate


In transition metals, the electrons go up energy levels if they absorb photons and by going up to different sub shells, hence why transition metals with full subshells don't absorb photons; there aren't any sub shells that electrons can 'jump' up to. In Benzene, the electrons are delocalised, so I'd imagine there aren't 'subshells' they can jump up to/down from, meaning they don't absorb any photons.


The absorption occurs in the mid-UV region (230-270 nm), and very strongly in the far-UV region (<210 nm). Since it doesn't absorb at all at visible wavelengths, it's colorless.
(edited 6 years ago)
Reply 4
Original post by MKaur18
In transitional metals, the electrons go up energy levels if they absorb photons and by going up to different sub shells, hence why transition metals with full subshells don't absorb photons; there aren't any sub shells that electrons can 'jump' up to. In Benzene, the electrons are delocalised, so I'd imagine there aren't 'subshells' they can jump up to/down from, meaning they don't absorb any photons.


The absorption occurs in the mid-UV region (230-270 nm), and very strongly in the far-UV region (<210 nm). Since it doesn't absorb at all at visible wavelengths, it's colorless.


Thanks very much:smile:

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