Question
Sun April 19, 2015 By: Shubhi Gupta

How density of unit cell is same as density of a substance?
Explain in detail with the help of an example.

Expert Reply
Hanisha Vyas
Mon April 20, 2015
Dear shyamageeta@yahoo.com

Thanks for asking us a question in Ask the Expert section of TopperLearning.com.

We have not understood the query that you have posted. We would request you to clarify / provide additional details so that we may answer this to the best of the ability.
 
However, you can refer to the following explanation/solution for the query you have asked,
Unit cell is the smallest group of atoms which has the overall symmetry of a substance (crystal), and from which the entire lattice can be built up by repetition in three dimensions.
For example unit cell of sodium chloride crystal has the overall symmetry of a crystal, and from which the entire lattice can be built up by repetition in three dimensions.
Hence, the density of unit cell is same as density of a substance which is given by the formula,
 
begin mathsize 12px style Density space of space the space unit space cell space left parenthesis straight rho right parenthesis space equals space fraction numerator Mass space of space unit space cell over denominator Volume space of space unit space cell end fraction space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space straight rho space equals space fraction numerator straight Z space cross times space straight M over denominator straight a cubed space cross times space straight N subscript straight A end fraction end style
Regards

Topperlearning Team.
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