Element flame tests

 

As is the way with Google oddities, I receive 50+ visitors per day to this blog looking for information on flame tests and flame testing techniques — odd, as the only reference to things “flame test” related is in this article on “Micrometeorites“.

So, I thought I’d see what was generally freely available on the Internet, provide a brief summary of what flame testing is and rate any useful resources I found – that way, if you end up on my blog, at least you can find something useful for your travels.

Firstly, if you are looking for a rounded book explaining flame testing of the elements, I would look no further than Periodic Tales which does a good job at making the elements exciting.

 

Wikipedia offers:

 

“A flame test is a procedure used in chemistry to detect the presence of certain metal ions, based on each element’s characteristic emission spectrum. “

 

 

Essentially, stick a metal ion into a Bunsen flame and it (might) change colour depending on the metal ion present.  Why?  It’s all to do with electrons and the Bohr model.  Add energy in the form of heat and electrons can be moved into higher energy orbitals.  When they fall back to their ground state, they release energy in the form on a photon of light of a particular frequency.

http://life.org.uk/ produced this video clip that explains it quite well:

 

 

What are the flame test colours? (from http://wesleydowler.com)

Table of elements and their flame test colours

Symbol	Name	Colour
As	Arsenic	Blue
B	Boron	Bright green
Ba	Barium	Pale/Apple green
Ca	Calcium	Brick red
Cs	Caesium	Blue-Violet
Cu(I)	Copper(I)	Blue
Cu(II)	Copper(II) (non-halide)	Green
Cu(II)	Copper(II) (halide)	Blue-green
Fe	Iron	Gold
In	Indium	Blue
K	Potassium	Violet
Li	Lithium	Crimson
Mn (II)	Manganese (II)	Yellowish green
Mg	Magnesium	No colour
Mo	Molybdenum	Yellowish green
Na	Sodium	Intense yellow
P	Phosphorus	Pale bluish green
Pb	Lead	Blue/White
Rb	Rubidium	Red-violet
Sb	Antimony	Pale green
Se	Selenium	Azure blue
Sr	Strontium	Red
Te	Tellurium	Pale green
Tl	Thallium	Pure green
Zn	Zinc	Bluish green

Internet resources

Site	Resource Type	Rating
Webmineral.com	Range of flame test colours and emission spectra	Suitable as general introduction and the emission spectra are useful.  No direct images of flame colours and no experimental techniques
Chemguide.co.uk	Details on “wire loop” method,  flame test colours and explanation of the origin of the flame test colours.	Upper GCSE / AS level explanation but easy to follow practical
Creative-chemistry.org.uk	Worksheet and teacher notes on flame tests.	KS3 level practical activity – the classic “identify the unknown white powder”
Wikipedia.com	Basic entry on flame test and photographs of tests themselves.	Flame test colours can be difficult to photograph as the CCD in the camera can distort the colours.

So, if you do end up here looking for flame tests, I hope this helps with your onward journey.