- #1
Joey V
- 4
- 0
Hi, so I'm a first year neuroscience student at Carelton University in Canada. I had a little bit of a "revelation" with this topic recently after I understood it a bit better and I think this is really interesting. (If I understand it correctly!) We're learning about Kekule structures, conjugation (alternating single/double bonds in a molecule) and color.
So basically what I understand is that, obviously, every wavelength of light has a different energy associated with it. This is the same for light photons. So when a light photon interacts with a molecule, it transfers its energy to the molecule and the photon is essentially "destroyed" or "absorbed". The length of the conjugate chain in the molecule plays a part in determining the wavelength of photon that gets absorbed by that molecule. So depending on how long the chain is, the difference in energy between the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital is affected.
What I understand is that when a photon (Let's pretend it's green) has roughly the same energy as the gap between the HOMO and LUMO, that photon will be absorbed by that molecule. This is because as the energy associated with the green photon bumps into an electron from the HOMO orbital and gives it energy to sit in the next orbital above it, LUMO. Now that the green photon just got absorbed we see all the other photons (or wavelengths of light) being reflected off of the object and we notice that there is no more green light being reflected off of the object. AKA we perceive that as "every color except green" or blue. (I think it's blue anyway).
Now this was the main part of my question:
If we turn off the lights in a room so that there is no visible light at all, do the objects that were originally absorbing green photons lose energy and have electrons drop back down to the HOMO orbital and lose their color? Essentially does this mean that in the dark, objects physically/chemically change and lose their color? Is this why we perceive shadows as being black, because an object is blocking photons from reaching the ground and since no (or less) photons are hitting the ground, it essentially has no color?
This was quite a doozy to write, thanks a lot for reading this and any answers, opinions or further questions would be greatly appreciated. I can't find anything on this on the internet so I'm going to ask my chemistry professor after the weekend and I'll update this thread after I get an answer from him.
Thanks again
So basically what I understand is that, obviously, every wavelength of light has a different energy associated with it. This is the same for light photons. So when a light photon interacts with a molecule, it transfers its energy to the molecule and the photon is essentially "destroyed" or "absorbed". The length of the conjugate chain in the molecule plays a part in determining the wavelength of photon that gets absorbed by that molecule. So depending on how long the chain is, the difference in energy between the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital is affected.
What I understand is that when a photon (Let's pretend it's green) has roughly the same energy as the gap between the HOMO and LUMO, that photon will be absorbed by that molecule. This is because as the energy associated with the green photon bumps into an electron from the HOMO orbital and gives it energy to sit in the next orbital above it, LUMO. Now that the green photon just got absorbed we see all the other photons (or wavelengths of light) being reflected off of the object and we notice that there is no more green light being reflected off of the object. AKA we perceive that as "every color except green" or blue. (I think it's blue anyway).
Now this was the main part of my question:
If we turn off the lights in a room so that there is no visible light at all, do the objects that were originally absorbing green photons lose energy and have electrons drop back down to the HOMO orbital and lose their color? Essentially does this mean that in the dark, objects physically/chemically change and lose their color? Is this why we perceive shadows as being black, because an object is blocking photons from reaching the ground and since no (or less) photons are hitting the ground, it essentially has no color?
This was quite a doozy to write, thanks a lot for reading this and any answers, opinions or further questions would be greatly appreciated. I can't find anything on this on the internet so I'm going to ask my chemistry professor after the weekend and I'll update this thread after I get an answer from him.
Thanks again