What is the edge length of a face-centred cubic unit cell made up of atoms having a radius of 128 pm?
A) 181 pm
B) 362 pm
C) 512 pm
D) 1020 pm

Question

Quizplus · Accepted Answer

The edge length (a) of the face-centred cubic (FCC) unit cell can be calculated using the formula:

a = 4r / √2

where r is the radius of each atom.

Substituting the given value of r = 128 pm (or 1.28 Å), we get:

a = 4(1.28 Å) / √2

a = 1.808 Å

Converting this to picometers, we get:

a = 180.8 pm

Therefore, the option closest to this value is B) 362 pm, which is twice the edge length of the unit cell.

What Is the Edge Length of a Face-Centred Cubic Unit