
Color of atoms (2014) - waqasaday
http://www.fnal.gov/pub/science/inquiring/questions/colorofatoms.html
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mysterypie
I can't even begin to list all the things confusing (or perhaps totally wrong)
about the Dept. of Energy's answer:

> _atoms do not have colors_

Then why do group of atoms (eg. gold) have a color, but not an individual
atom?

> _If the electrons give out exactly the same light as they absorb, the
> substance is "colorless"_

Shouldn't the answer be "white" rather than "colorless"? Colorless sounds like
transparent or clear to me.

He uses absorb, reflect, and emit inconsistently. Surely, there has to be a
clearer explanation somewhere on the Internet?

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thoughtifnot
> Then why do group of atoms (eg. gold) have a color, but not an individual
> atom?

I think the point is the question implicitly assumes you can take an atom,
blow it up to the size of a softball, and then observe what color the softball
is. It's correct to reply that atoms are actually a smaller-scale phenomenon
than color, so the color of the softball is "not applicable". (With the
correction pointing out that sometimes individual atoms _do_ exhibit "colored"
phenomena, although it's not the same as most colors, and doesn't apply to
most atoms.)

"If the atoms don't have color, why does the substance" is a great
philosophical question, similar to the question of why words have meaning, but
not letters. By analogy I'd probably start with something like "atoms make
color, but that doesn't mean they have it".

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seanp2k2
The words:letters analogy was great and helped me understand this better.
Thanks.

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etendue
Interesting, my first thought jumped to gold and the 5d->6s transition that is
well-known for needing relativistic consideration to correctly predict the
yellow color.

I don't think the answer given is a great one, but I like that they sent a
correction.

