Flame Test for All Elements

name         Jocelle
status       student
grade        9-12
location     N/A

Question -   Can the flame test be used to identify all of the elements?
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Jocelle,

If by "flame test" you mean some kind of dipping a gauze in a 
solution of the target element and then heating that solution in a 
Bunsen burner, or perhaps, directly heating a sample in a flame - then no.

Some elements, like hydrogen, will react with the ambient oxygen 
when applied to a flame and it is the light from this reaction that 
you see - and not the color of hydrogen. Some elements are not 
easily accessible (like the heavy metals) and I am not even sure 
that we know the colors produced by such elements.

However, if by "flame test" we mean the broader notion that each 
individual element has its own specific line spectrum (when the 
light produced upon heating the element is passed through a slit and 
the sliver of light is passed through a prism or a diffraction 
grating), then, yes, we can identify all the elements in this way. 
There are, for example, hydrogen gas lamps that will allow us to 
pass an electric arc through the gas - and will give off its 
characteristic line spectrum.

Greg (Roberto Gregorius)
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Although every element has a characteristic emission spectrum, not 
all elements have electronic transitions that can be produced by the 
temperature of a flame from a burner or torch. Many, if not most 
elements, require a higher energy excitation source to produce 
visible emissions.

Vince Calder
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Jocelle,

In short, yes, a flame test can be used to identify all of the 
elements, but you cannot use your eyes as a detector.  You must use 
a diode array detector that detects all wavelengths at 
once.  Without going into too much theory, what happens is the flame 
excites the electrons of a particular atom, then those electrons get 
promoted to higher energy levels (shells).  Eventually the electrons 
will relax back to their resting state and when this happens they 
emit the energy that they absorbed as a photon of a particular 
wavelength.  This wavelength(s) are unique for each atom because 
each atom has a different electron configuration.  Not only can you 
identify the atoms present, but you can also quantitate how much is 
present as well.

Matt Voss
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