1. The problem statement, all variables and given/known data Calculate the Fermi energy, EF at 0K for potassium (atomic weight = 39, density = 860 kgm3). 2. Relevant equations KF3 = 3π2n Fermi Momentum ρ = h(bar)KF 3. The attempt at a solution: For the first part: Using: E = ρ2/ 2m Can substitute Fermi momentum into that to get: EF = h(bar)2 KF2 / 2m KF2 = √(3π2n) = π√(3n) Putting all the together I got: EF = h(bar)2 π √(3n) / 2m which is the same as: EF = h2 √(3n) / 4m I'm not too sure what to do after this point as i'm not sure how the atomic weight or density can give me a value for n and m. I do have written in my notes that n = N/v but again I wasn't sure how this would help me. I feel like I must be going down the wrong path to come out with an equation that needs completely different things to what the question is providing me with. But honestly I have just started this condensed matter course and haven't really got my feet yet. Thanks in advance to anyone that replies.