Why is the colour of the light emitted by an element in the gaseous state characteristic of the element?
Various elements absorb some wavelengths while letting others move on.
Since this is not my area of expertise, I searched Google under the key words "Spectrum elements explanation" to get these possible sources:
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http://online.cctt.org/physicslab/content/Phy1/lessonnotes/atomic/atomicmodelsandspectra.asp
I hope this helps. Thanks for asking.
Brilliant, thanks