# Face centered cubic question

#### starrysky

The atomic radius of metal X is 1.50 × 102 picometers (pm) and a crystal of metal X has a unit cell that is face-centered cubic. Calculate the density of metal X (atomic weight = 42.3 g/mol).

#### topsquark

Forum Staff
The atomic radius of metal X is 1.50 × 102 picometers (pm) and a crystal of metal X has a unit cell that is face-centered cubic. Calculate the density of metal X (atomic weight = 42.3 g/mol).
The main concept here is to find the density of the material...ie. from a single unit cell. So for an FCC crystal how many atoms of X are in the unit cell? What are the dimensions of the unit cell? So now you know the density in terms of # of atoms/volume in a unit cell. The rest is unit conversions.

Does this help or do you need more?

-Dan

#### chemistrystudy

We know that σ = (Z × M)/(N × a³)

Here, Z = 4 for fcc cubic Crystal, M = 42.3 gm/mol and N = 6.023 × 10²³ and a = 1.50 × 10² pm = 1.50 × 10⁻⁸ cm

Putting the value on the above equation to calculate the density of the crystal X.

Similar Chemistry Discussions Chemistry Forum Date
High School Chemistry