do the positive ions or the negative ions cause the change in flame color?
4 answers
Mostly positive.
can you please explain why
I don't think it's a matter of which ions are excited versus those that are not as much as it is the color. Atoms/ions that are used in flame emission are there primarily for three reasons:
1. They are easily volatilized in a flame and
2. They emit energy that places the wavelength in the visible part of the spectrum and
3. The lines they emit in the visible part of the spectrum are very intense.
You will notice also that most of the useful one for flame spectroscopy are low in the periodic table such as Na K Li etc.
Cl^-, Br^- etc are volatilized in the flame, also, but there are no STRONG (intense) lines in the visible region of the spectrum as in Na, K, etc.
By the way, you may find it interesting to know that the green line for Ba and the red line for Sr are NOT due to Ba and Sr but they are band spectra of BaO and SrO.
1. They are easily volatilized in a flame and
2. They emit energy that places the wavelength in the visible part of the spectrum and
3. The lines they emit in the visible part of the spectrum are very intense.
You will notice also that most of the useful one for flame spectroscopy are low in the periodic table such as Na K Li etc.
Cl^-, Br^- etc are volatilized in the flame, also, but there are no STRONG (intense) lines in the visible region of the spectrum as in Na, K, etc.
By the way, you may find it interesting to know that the green line for Ba and the red line for Sr are NOT due to Ba and Sr but they are band spectra of BaO and SrO.
damn this was 2013 so long ago
2 answers