September 20, 2021, 07:36:06 AM
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Topic: flame test  (Read 3096 times)

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Offline researcher

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flame test
« on: November 20, 2009, 10:04:53 AM »
 I don't understand why copper(I) and copper(II) have different flame colors. I thought it was a characteristic of the metal, can anyone explain?

Offline cth

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Re: flame test
« Reply #1 on: November 20, 2009, 10:27:49 AM »
Absorption/emission of light depends on the electronic configuration of an element.

When an atom absorbs a photon, one of the electrons goes from the ground state to an excited state. Then, it goes back to the ground state by emitting the photon it had absorbed, with the same wavelength (at least for simple cases). That wavelength depends on the energy gap between the ground state and the excited state.

The number of electrons for CuI and CuII are different. So, the possibilities to excite an electron are different  :rarrow: different colors.

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