Number of particles and unit cells in x g of metallic crystal

Combining the density relation (Eq. 1.4) with Avogadro's number lets us count the particles -- and the unit cells -- present in any given mass of a metallic crystal.

• Number of particles in '$x$' g metal : The molar mass $M$ contains $N_A$ particles, so $x$ g of metal contains $\dfrac{x\,N_A}{M}$ particles. From Eq. (1.4), $M = \dfrac{\rho\,a^3 N_A}{n}$; substituting,

• Number of unit cells in '$x$' g metal : Each unit cell contains $n$ particles, so …