[galpinj]

Hey everyone,

I read on wikipedia that copper (II) nonhalide will have a green colour while copper (II) halide will have a blue-green colour. I'm curious what causes this difference, as the copper atom still has the same amount of electrons and, I assume, should be providing similar emissions.

When looking at copper (I) or copper (II), does the colour difference come from the variance in electron number? I had read that in flame tests it is always the atom, and not the ion, that produces the colour, so I'm stumped as to why copper can have this variation.

Thank you!

[Hunter2]

You are right. The color comes from the Ion. The difference is only that copperhalids easly to get in gaseous form in flame and the flame is more intensive green-blue coloured.

[galpinj]

Ah, I see!

I had read that the cation would, with the energy from the flame, regain it's two electrons (become the atom copper) and it was the resultant changes in energy level of the copper atom (not ion) that made the color. Would you say this is incorrect? What electrons would be moving energy levels in the cation?

Thank you