Why do the the alkali metals give blue solution ,when treated with liq NH3?

Why do the the alkali metals give blue solution ,when treated with liq NH3? 
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1 Answer

Answer :

The alkali metals dissolve in liquid ammonia giving deep blue solutions which are conducting in nature.

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The blue colour of the solution is due to the ammoniated electron which absorbs energy in the visible region of light and thus imparts blue colour to the solution. The solutions are paramagnetic and on standing slowly liberate hydrogen resulting in the formation of amide.

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 (where ‘am’ denotes solution in ammonia.) In concentrated solution, the blue colour changes to bronze colour and becomes diamagnetic.  

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