Burning Elements - Visible Light Spectrum


by MadmanMurray
Tags: burning, elements, light, spectrum, visible
MadmanMurray
MadmanMurray is offline
#1
Nov5-08, 02:23 PM
P: 76
We did a chemistry experiment were we burned different metal chlorides on the bunsen to observe the different flame colors produced. Anyhow I'm writing up the report but theres one thing I'm not sure about. I can't make any mistakes because I made the mistake of displaying way too much chemistry knowledge at the start of the year and now the teacher shows no mercy with me. He lets me away with no mistakes.

The teacher explained that the different colors are caused by the different amounts of electrons and energy levels present in the different elements. The elements burned were copper, stronium, lithium, sodium, potassium, barium and calcium. The chloride salts of these elements I mean. I don't know how to explain this I was gonna say "I concluded that the different elements when burned give different ranges of light from the visible light spectrum which is evident by the different colors of light radiated by the different elements when burned".

Is this correct? Do the elements radiate "ranges" of light from the spectrum or do they just radiate dispersed wavelengths of light? The teacher told us that high electron/energy level elements such as copper radiate a wider variety of colors which is why the flame produced by copper is more yellow/white and closer to white light which contains all the colors in the spectrum. Would it be accurate for me to say that elements with large amounts of electrons/energy levels radiate a broader range of light from the visible light spectrum than lighter elements do?

EDIT: I just checked the period table and noticed what I said doesn't make sense. Copper burns with a whitish light but strontium which is higher up on the table burns with a red light. Red light is obviously missing a lot of the color spectrum.
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Walter Hynson
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#2
Jul13-11, 07:51 PM
P: 1
the color of the light from an element that is either arched or sparked is determined by the level of energy needed to release the ion from the initial element also every piece of copper that I have arched is always green and shows a line in the green or 5000 to 5500 Angstrom range ,yes you will get other lines however these may be due to impurities or other matels in the alloy you are testing,since you were using a bunsen burner the white light may have been caused by th burner itself,also checkout a book called blowpipe analys or other very old book on optical spectro analysis......WCH
Drakkith
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#3
Jul13-11, 08:19 PM
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You are missing a key piece here. EM Radiation emitted by something isn't always in the visible spectrum. For example, the spectral lines detected from Hydrogen were first observed in the visible range, but when QM (Quantum Mechanics) was first developed it was PREDICTED that even more spectral lines would exist past the visible light range. This was observed several years later and agreed with QM.

Is this correct? Do the elements radiate "ranges" of light from the spectrum or do they just radiate dispersed wavelengths of light?
I'm not sure what you mean. Each color is a small range in the EM spectrum. There is no specific wavelength with is the standard for that color. Instead it is the range from x-y wavelengths that are called Red or Green. Even the spectral lines are not a single wavelength, but have a small range because of quantum and relativistic effects that cause the energy of the electrons to vary slightly. If something has multiple lines within the visible spectrum, it will show up to you as a single color.


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