pls answer these qus. about coulours of elements?

Question

1) what is the reason of an element's having a colour?
2) the alkali and alkaline metals have colours due to electron transition. do they always go on doing this as they are always colourfull?
3) if colours are releted to absorbing of colour spectrum, what is the reason of transparency?

Answer 1

1) refraction by electrons

2) The alkali and alkaline earth metals are white in colour. No electron transition occurs.

3) Transparency occurs when sufficient light can pass through the substance. This can be assured through less scattering of light by atoms and electrons.

Answer 2

Well, these colors are observed during a flame test and basically represent the jump of electrons from ground energy level to a higher state (due to the heat energy from the fire). As they return to the ground state, they emit visible light...

Here's what About.com says:

"The color also is connected to the location of the electrons and the affinity for the outer shell electrons to the nucleus. As you have noted, the color of the larger atoms is lower in energy. Sr giving a reddish color as compared to Na orange color. The Na is has more affinity for the electron therefore it takes more energy to move the electron and thus the electron goes to a higher excited state. As the electron descends to the ground state it has more energy to disperse."

And I have no clue what you mean by the last question...you can read about it on this link though cos it will probably mean more to you than to me...

http://en.wikipedia.org/wiki/Electromagnetically_induced_transparency

Hope this helps at least a little!