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I have done a flame test with $\ce{NaCl}$ and got the yellow characteristic flame of sodium. I am trying to understand exactly how this yellow color is being produced and when I searched for it, I got conflicting answers.

I understand that it is being produced by excitted electrons that fall back and produce photons. I also understand that different elements have different energy levels for their electrons so when the electrons fall back, they will produce a different wavelength of photon and therefore a different color.

What I was trying to find out is whether the sodium that gets excited is still bound to the chlorine or if it is dissociated, becoming a free ion and then excited.

Most sources said the sodium ion is dissociated and then excited, but some sources argued the yellow flame is apparently produced by electrons getting excited from the 3s orbital to 3p and the sodium ion doesn't have the electron in the 3s orbital which is being excited, therefore it is actually a neutral sodium atom which is being excited. Would a neutral sodium atom, a sodium ion and a sodium ion bound to chlorine produce different colors when excited? And if the sodium ion is dissociated and then excited, then why does the anion still sometimes affect the color of the flame?

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    $\begingroup$ There's no ions in gas - you need plasma for that. $\endgroup$
    – Mithoron
    Jun 9, 2023 at 18:20
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  • $\begingroup$ @Mithoron Thank you! It confirms some of my assumptions and answers part of my question, but I am not completely satisfied with the answers on the other questions. What I am mainly wondering about is if the sodium dissociates from the chlorine and if it is a free sodium ion which gets excited. The answer mentions that the sodium gets ionized, but the answer also mention again that the yellow color is caused by electrons from the 3s to 3p orbital, but I still don't understand how that is possible in a sodium ion. $\endgroup$
    – Tuskies
    Jun 9, 2023 at 18:35
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    $\begingroup$ The sodium emission is shown here: chemistry.stackexchange.com/a/164168/79678. The emission is from excited sodium atoms, not sodium ions. In the flame, there are various species, including excited sodium atoms, chlorine atoms, some NaCl molecules and some ions, though not many in an ordinary flame such as I show in my linked answer. The flame is electrically neutral, as expected. $\endgroup$
    – Ed V
    Jun 9, 2023 at 19:22

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