1. The problem statement, all variables and given/known data The movovalent metal Na (sodium) has the body-centred cubic structure with a unit cell side length of 4.23 x 10^-10 m What is the free electron density of sodium? 2. Relevant equations 3. The attempt at a solution I used: n = (6.02 x 10^23)(density of sodium) / (atomic mass) = 2.54 x 10^28 m^-3 But isnt this the number of atoms per unit volume not free electron density? Thanks.