The density of chromium metal is `7.2 g cm^(-3)`. If the unit cell is cubic with edge length of 289 pm. Calculate the number of atoms per unit cell. (Atomic mass = 51.79)

Explanation

Formula:
`d= 7.2 g cm^(-3), a=289 xx 10^(-12)`
`a = 289 xx 10^(-12) m xx 10^(2) = 289 xx 10^(10) cm = 2.89 xx 10^(-8)` cm
`N_(A) = 6.022 xx 10^(23), M= 51.79`g
`d=(Z xx M)/(a^(3) xx N_(A))`, `z=(d xx a^(3) xx N_(A))/M`
`Z = (7.2 xx (2.89)^(3) xx 10^(-24) xx 6.023 xx 10^(23))/51.79`
Z=2 atoms.