Atoms and their light spectrum
In a hot flame, atoms can acquire so much energy that some electrons (sometimes but not always the valency electrons) become enormous moving, and they can not longer remain at their fixed position: they become in an 'exited state' in stead of staying in their 'ground state'.
For a moment they leave their own energy level and remove themselves a bit further from the atom nucleus.
Then you can have two options:
- Such an electron (mostly a valency electron)has got enough eneregy to remove completely from the atom. Thus an ion is formed, and we talk about 'ionisation' of the atom.
The needed energy for that is called the ionisation energy.
There are table showing ionisation energy of atoms.
- Such an electron (in this case mostly not a valency electron) does not get enough energy to remove completely. It just goes to a bit higher energy level. No ion is formed but yes, an exited state. And an exited state is not stable. (as everyone knows). This has to go back to its original state, ground state.
Going back means: the before gained energy must get lost. The electron cannot go back to the old energy level and keep its newly gained energy. This loss of the energy often occurs in the form of electromagnetic radiation (can be visible light). In that case you can observe a color effect.
Every type of atoms causes in this way its own light spectrum.
| Sodium |
yellow |
|
Copper |
green |
| Potassium |
weak violet |
|
Stannium |
blue |
| Calcium |
red |
|
Lead |
weak blue |