something about the distance between the electron levels

so conjugated systems (shit with double bonds) usually have lower energy levels, that allows for electron transfers of the appropriate energies to correspond to visible light

Speaking with 1 semester of Chemistry background

>>7667540
You're basically right. Essentially for light to be emitted an electron needs to go from an excited state to a lower energy state. The released energy will be in the form of a photon. A heavily conjugated pi-bond system will have smaller energy difference between the highest occupied and lowest unoccupied orbital (energy level, essentially). Some of them are low enough to be in the visible range.

As for shiny vs matte that's a tad bit more complicated, despite involving less QM. I'm not 100% sure but I think, for a given material, the biggest factor is actually the angle of incidence that the light hits the surface. As well as how smooth the finish on the surface is.

>>7667552
So something like biphenyl won't have much of a color because it has many pi bonds, but a diatomic molecule pair of hydrogen or chlorine will?

>>7667566
No that's just about the opposite of what I said. I'm don't remember my Woodward-Fieser rules enough to predict what color biphenyl will have but I'd guess it'll be somewhere in ultraviolet.

Hydrogen and chlorine are not organic molecules and don't have pi systems, so you can't make the same argument. Depending on what energy levels you excite (and if it's even possible to excite them!) you may get color.

>>7667585
I completely misinterpreted what you said. Holy shit. Highly conjugated systems delocalize their electrons to become more stable, and thus the bond with the "highest" energy will be similar to the bond with the "lowest" energy. Sorry about that.

I intended for my original question to be about the colors of things as they sit rather than spectroscopy. Why is pure sulfur yellow and pure graphite black, etc.

>>7667607
>pure graphite
pure carbon in the form of graphite*

>>7667607
Well the same logic still applies, it's all about what energy photons the molecule can reflect, which is governed by its energy levels.

And if you're wondering how something can absorb "all" light and only reflect certain wavelengths, well that's because the other wavelengths aren't emitted as photons, only as phonons. They change the vibrational and rotational state of the molecule, not its electronic state. So the more light it absorbs, the hotter it gets.

Sulfur happens to absorb all visible wavelengths except yellow, which it ejects as a photon. And graphite aborbs all visible wavelengths.

>>7667639
That's pretty fuckin neato senpai.

You might want to look at this:
https://en.wikipedia.org/wiki/Structural_coloration

There are different ways than just the jumping of an electron from one orbital to another to give the impression of colour.

>>7667509

Read up on color field theory.

It does an okay job at explaining both color and magnetism.

metals have fully delocalized electrons, their enery levels are quasi-continuous, so the electrons can be excited by all wavelengths equally. This also means that they reflect all wavelengths equally and therefore are shiny.