1. The problem statement, all variables and given/known data Calculate the number [itex]n_0[/itex] of electrons per volume unit in the conduction band for the lithium, copper and aluminium. Compare this result with the number of electrons of valence per volume unit of these metals. 2. Relevant equations None given, no ressource either. Currently checking out this: http://hyperphysics.phy-astr.gsu.edu/hbase/solids/band.html#c6 but I don't see how this can help me for that problem. 3. The attempt at a solution Basically stuck at start, I've checked out in 3 books (Brehm's, Serway's and Alonso&Finn's) +the Internet about this and couldn't find how to start the problem. What I imagine is that since they are 3 good conductors, the conduction band must be somehow filled so that I expect the number of electrons per volume unit in the conduction band to be "high" or about the same order of magnitude than the number of electrons per volume unit in the valance band. I don't really know how to show this mathematically though. I guess I'll have to check out the electrical configuration of the lithium to start with. From memory it's [itex]1s^22s^1[/itex]. And this is where I'm stuck, I don't know what to do next. Thanks for any help, even if it's redirecting me to books/websites!