Flame test

Origin of Flame Colours

• Flame colours are produced from the movement of the electrons in the metal ions present in the compounds.
• For example, a sodium ion in an unexcited state has the structure 2.8.1.
• When you heat it, the electrons gain energy and can jump into any of the empty orbitals at higher levels, depending on how much energy a particular electron happens to absorb from the flame.
• Because the electrons are now at a higher and more energetically unstable level, they tend to fall back down to where they were before - but not necessarily all in one go.
• An electron which had been excited from the 2nd level to an orbital in the 7th level, for example, might jump back to the 2nd level in one go. That would release a certain amount of energy which would be seen as light of a particular colour.
• However, it might jump back in two (or more) stages. For example, first to the 5th level and then back to the 2nd level.
• Each of these jumps involves a specific amount of energy being released as light energy, and each corresponds to a particular colour.
• As a result of all these jumps, a spectrum of coloured lines will be produced. The colour you see will be a combination of all these individual colours.
• The exact sizes of the possible jumps in energy terms vary from one metal ion to another. That means that each different ion will have a different pattern of spectral lines, and so a different flame colour.

By adding different metals into a flame, the colour of the flame would change.
The colours of the flame
Barium - pale green
Calcium - red-orange
Copper - blue-green
Lead - White-blue
Potassium - Lilac
Sodium - Bright yellow

 Copper 

 Sodium 

Potassium 

Here's a cool video!!

However, there are some substances that does not change colour when added to the flame. This would mean that the substance added is not a metal.


Human remains

The human body contains only about 1g of silicon and this is the element that will survive the heat of the crematorium oven. The content in the urn will therefore be less than 1%, a small fraction of the human ashes.
The analysis in the lab showed that the percentage of silcon is 19% hence proving that it can't be of human origin.



The videos showing the different flame colours will be uploaded soon