Flame test

Hey.

I understand why certain elements turn different colours when put into a flame and all that crap. But i dont understand why not every element does it. Which elements can do it? And why cant the elements that cant do it, do it?? Confuzzling eh!!

 

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Let me see if i remember...hopefully someone after me will explain it better. I think that all the flame does is add energy, or "excite" the atom of the particular compound being flamed. Hm..curpic chloride (CuCl2), when thrust in the flame, will produce a green/blue color. Copper just does that. It shows up blue/green in a flame test. Why? Basically, the atoms are exciting and give off some color..i'm not sure about the details though. Some elements/compounds arent easily excited i guess, that's why the flame test doesnt work for them. Hope i've helped

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Oh, and people that post after me, if i was wrong (probably was), go ahead and correct me, i wont mind

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One of the problems is in applying temperature. If the temp is not hot enough then there will be no tell tale emmision bands. Some elements require more than others.

A lot of them require more heat than will be available to say, a high school lab where safety is a consideration.

 

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Ya,

Well, there are a couple things that could conceivable happen, a reaction could occur releasing light, and what will always happen will be that the electrons in the atoms will be "excited" meaning they will move faster.

I don't know much about how light works, but as I recall, different atoms and molecules release different light, which has to do with their specific electron system. Every atom and molecule releases some kind of light, not neccessarily visable light though.

A factor of a "flame test" is the heat of the flame, so different heats could produce different results.

 

Thanks! But does anyone know why some elements dont give out light when shoved into a flame?

 

If I am reading the posts above yours correctly, it is because a the light is not in a wavelength visible to the human eye, and/or a flame does not give off sufficient heat energy to excite the molecules. Something hotter is required.

Peace.

_____________
Youth is the first victim of war - the first fruit of peace.
It takes 20 years or more of peace to make a man;
it takes only 20 seconds of war to destroy him.

• -- King Boudewijn I, King of Belgium (1934-1993)

 

Ah! Now i understand! Thanks!

 

What you are seeing, when you see colored flames, is electrons dropping back from an excited state to a rest state. The heat of the flame pushes some electrons to a higher energy level, when these electrons drop back to the rest state they give off a photon. The energy of that photon (light) corresponds to the energy difference between the two states.
Now if that energy difference give you a photon in the visible region of the spectrum you'll see some light. That is the color in the flame. If the photon energy falls in the infrared region you won't see any light (visible to your eyes ). Of course some of these transitions can be in the ultraviolet or enven higher energy levels and in that case the flame may not be hot eneough to excite the electrons to the higher band anyway.
If you look at the periodic chart you'll notice that elements which make colored flames fall in groups on the chart. Generally flames towards the red/yellow end are brighter too, that is probably since it takes less energy to make a red photon. Blue color is harder to make, the photon take more energy, and you'll notice that fireworks are mostly red and yellow with only occasional blues. The blue is harder and more expensive to make.

 

it all boils down to the chemical make-up of a ...er, well, not to be redunant, but, the chemical itself. some have a molecular structure which allows for flamability...some don't. eh....

 

Welcome to sciforums, Agesilaus and pumpkinsaren'torange.

 

Thanks! Nice to be here.

 

Well actually emission lines are primarily a function of electron states, molecular species can modify the lines but this is a minor effect.

 

mmmmmmmuhaha.......*smacks forhead with palm of hand* ......... i MEANT to say: "redundant" ...not, redunant.....hooooohoo hooo. btw...guys, thanks for the welcome...i am a science hound...oh, yeah. biology, chem. (organic, preferably..

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) .... woof. woof. i shall write some more in a bit...i have been thinking about vectors. vectors are a mighty good thing...those and plasmids. whadya think? hmm?

 

If the number were written out it might extend from one end of the universe to the other. Pretty trippy, huh?

 

It appears that I've been totally tripped out, so much in fact that I posted the wrong message in the wrong thread. Sorry.

 

woot!!!!!!!!!

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Technically every material radiates a certain amount of energy. Usually though it is at infra-red level or lower. If we had a wider spectrum we could see in the flame test would work for just about everything.

 

:bugeye: a spider spectrum????


oh, wait....

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Preferable to a spider speculum.

 

gonna have to be a mighty small speculum...

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