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Offline Don_1

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What colour are atoms?
« on: 11/04/2009 17:08:40 »
I've posted this here for the benefit of the poor chemistry crowd, who sometimes feel a little left out, but really, I suppose it should be a physics question, ah well!

What colour are atoms?

Almost everything has a colour, or at least it absorbs some of the spectrum of the light which strikes it and reflects the remainder, giving the appearance of a recognised colour. When we look at some elements, in their pure form, they too have colour. For example Au (gold) is, well, gold! And Ag (silver) is erm, silver and Cu (copper) which is ----- yep, copper. Then there are the not so obvious elements such as S (sulphur) which is yellow and Co (cobalt) which is grey.

Now if I took some copper coloured paint and mixed it with a yellow paint, I would get a very light orange colour. So it follows that if I take Cu (copper) and combine it with S (sulphur) and (O) oxygen, which is colourless, I will get copper sulphate (CuSO4) which is of course a light orange colour BLUE??? How does this happen? All atoms are made of the same protons, electrons and neutrons (+ the odd few other bits, thrown in for good measure) in varying quantities.

So what is it about atoms that make them absorb and reflect light differently? And how can joining different atoms together to form molecules of compounds have such a radical effect on their light reflexion properties?


 

Offline lightarrow

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What colour are atoms?
« Reply #1 on: 11/04/2009 19:06:28 »
I've posted this here for the benefit of the poor chemistry crowd, who sometimes feel a little left out, but really, I suppose it should be a physics question, ah well!

What colour are atoms?

Almost everything has a colour, or at least it absorbs some of the spectrum of the light which strikes it and reflects the remainder, giving the appearance of a recognised colour. When we look at some elements, in their pure form, they too have colour. For example Au (gold) is, well, gold! And Ag (silver) is erm, silver and Cu (copper) which is ----- yep, copper. Then there are the not so obvious elements such as S (sulphur) which is yellow and Co (cobalt) which is grey.

Now if I took some copper coloured paint and mixed it with a yellow paint, I would get a very light orange colour. So it follows that if I take Cu (copper) and combine it with S (sulphur) and (O) oxygen, which is colourless, I will get copper sulphate (CuSO4) which is of course a light orange colour BLUE??? How does this happen? All atoms are made of the same protons, electrons and neutrons (+ the odd few other bits, thrown in for good measure) in varying quantities.

So what is it about atoms that make them absorb and reflect light differently? And how can joining different atoms together to form molecules of compounds have such a radical effect on their light reflexion properties?

The answer is very long...So I'll give you just a few hints here (I can't write an encyclopedy...)
1. The colour of bodies is not the colour of their atoms.
2. The colour depends on a lot of things (even remaining in physics, but it's also a subject of physiology and psychology).
3. In the specific case of CuSO4*5H2O (the anydrous salt is white) the colour is due to a charge transfer between the Cu++ ion and the H2O molecules.
 

Offline Raghavendra

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What colour are atoms?
« Reply #2 on: 12/04/2009 07:41:15 »
Can u explain detail, or post a link of website
 

Offline Chemistry4me

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Offline Raghavendra

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What colour are atoms?
« Reply #4 on: 12/04/2009 07:56:24 »
thanks C4M
 

Offline Don_1

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What colour are atoms?
« Reply #5 on: 13/04/2009 14:10:53 »
Thanks for this C4M.
 

Offline Raghavendra

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What colour are atoms?
« Reply #6 on: 15/04/2009 09:06:45 »
Color
 

Offline dentstudent

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What colour are atoms?
« Reply #7 on: 15/04/2009 09:11:52 »
Color

If you speak US English, then yes. In all other cases, it is colour.
 

Offline Chemistry4me

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What colour are atoms?
« Reply #8 on: 15/04/2009 09:13:00 »
It's colour okay? Please don't argue.
 

Offline Bored chemist

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What colour are atoms?
« Reply #9 on: 15/04/2009 20:47:42 »
OK, this may be a bit off- topic but is  just one word
Color
the author's least useful post yet?

Anyway, the reason that, for example, copper sulphide (black) is a different colour from a mixture of (yellow) sulphur and (reddish) copper is that when the two elements react they shuffle the electrons about- the sulphur picks up a couple of electrons from the copper. Since the colour of an element is essentially based on the energy levels of the electrons, it's not suprising that the colour changes when the electrons get pinched from one atom by another.

(oh BTW, C4M the colour of blue vitriol is due to electrons being moved about within the d orbitals on the copper- charge transfer colurs are generally much more intense. Compare the blue of aqueous coper (II) to the intense purple of permanganate)
« Last Edit: 15/04/2009 20:52:08 by Bored chemist »
 

Offline Chemistry4me

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What colour are atoms?
« Reply #10 on: 16/04/2009 01:49:40 »
(oh BTW, C4M the colour of blue vitriol is due to electrons being moved about within the d orbitals on the copper- charge transfer colurs are generally much more intense. Compare the blue of aqueous coper (II) to the intense purple of permanganate)
I don't believe I have said anything about blue vitriol. ???
 

Offline Bored chemist

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What colour are atoms?
« Reply #11 on: 16/04/2009 08:04:40 »
(oh BTW, C4M the colour of blue vitriol is due to electrons being moved about within the d orbitals on the copper- charge transfer colurs are generally much more intense. Compare the blue of aqueous coper (II) to the intense purple of permanganate)
I don't believe I have said anything about blue vitriol. ???
Oops! It was Lightarrow.
 

Offline lightarrow

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What colour are atoms?
« Reply #12 on: 16/04/2009 13:00:18 »
(oh BTW, C4M the colour of blue vitriol is due to electrons being moved about within the d orbitals on the copper- charge transfer colurs are generally much more intense. Compare the blue of aqueous coper (II) to the intense purple of permanganate)
I don't believe I have said anything about blue vitriol. ???
Oops! It was Lightarrow.

I think that you are right, but I wonder how the water molecule's field affect the color of the metallic ion (I'm pretty sure it has different colours in different solvents).
 

Offline Bored chemist

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What colour are atoms?
« Reply #13 on: 16/04/2009 21:08:03 »
True, but the orbitals are still largely on the metal.
Those who wish to look more deeply into it could start here
http://en.wikipedia.org/wiki/Cfse
 

Offline lightarrow

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What colour are atoms?
« Reply #14 on: 17/04/2009 00:13:52 »
True, but the orbitals are still largely on the metal.
Those who wish to look more deeply into it could start here
http://en.wikipedia.org/wiki/Cfse
I've understood better now. Thanks for the link!
 

Offline cedar_tree

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What colour are atoms?
« Reply #15 on: 18/04/2009 01:43:26 »
just how could light photons reflect if the proton and the neutron sizes are smaller than the visible spectrum of light itself? I thought the electron football Field with a pin head nucleus reflected its spin and orbital speeds with a rack in a pinion example throwing some light wavelength's back at the observer. (nobody cared)

it doesn't reflect any color of light under 100 Nanometers, its a wavelength unit itself. Says the CERN particle accelerator in France.  cant mess with this website!

how is reflection the question with unmatched particle sizes? A hole punching laser tech help prove this for me.
« Last Edit: 18/04/2009 01:47:18 by cedar_tree »
 

Offline Chemistry4me

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What colour are atoms?
« Reply #16 on: 18/04/2009 01:49:06 »
You should start a new thread.
 

Offline Bored chemist

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What colour are atoms?
« Reply #17 on: 18/04/2009 18:35:46 »
You should start a new thread.
I'm not sure about that. I think he just shouldn't have bothered posting.
 

Offline Chemistry4me

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What colour are atoms?
« Reply #18 on: 19/04/2009 02:20:18 »
I think we've scared cedar_tree away.
 

Offline Bored chemist

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What colour are atoms?
« Reply #19 on: 19/04/2009 15:12:24 »
I live in hope (actually, I go past the turn off to Hope on the way to work.)
 

Offline Chemistry4me

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What colour are atoms?
« Reply #20 on: 20/04/2009 01:39:30 »
I think he must be petrified stiff. Geddit?
 

Offline Bored chemist

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What colour are atoms?
« Reply #21 on: 20/04/2009 22:26:37 »
I think he must be petrified stiff. Geddit?
Groan!
(or should that be "grown"?
 

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What colour are atoms?
« Reply #21 on: 20/04/2009 22:26:37 »

 

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