Question

Derive an expression for density of
a cubic crystal
of an element in terms of S.I units​

Answer 1

Answer:

Explanation:

Density = mass of 1 unit  / volume of 1 unit

Let the edge of cubic  = q

volume = q^3

The atoms are in contant along the face digaonal BD. Let a be the edge length and r, the radius of an atoms.

Consider a triangle BCD.

BD2=BC2+CD2

=a2+a2=2a2

∴ BD=2a−−√

From figure BD = 4r

∴ 4r=2–√a

∴ r=2–√4a=a22–√

r=a22–√