what are F-centres?.... How are they responsible for imparting diff colors to comp...(KCl, NaCl)..?

Asked by  | 27th May, 2008, 08:45: AM

Expert Answer:

when the crystals are heated in Na vapour, the Na atoms are deposited on the surface of the crystal. The Cl- ions diffuse to the surfaceand combine with Na to give NaCl. This happens by the loss of e- by Na atoms to form Na+ ions. The released e- difuse into the crystaland occupy anionic sites. As a result the crystal has excess of Na. the anionic sites occupied by the unpaired e- are called F-Centers . They impart yellow colour to NaCl. Pink to LiCl and lilac to KCl.

Answered by  | 27th May, 2008, 06:16: PM

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