I am taking Solid State now and using Kittel as the textbook. Needless to say, I don't understand almost anything that's happening. I'm still stuck on Reciprocal Space here. If I have a lattice of atoms of spacing X, then in reciprocal space I get something like 2*pi/X spacing. My prof. explained that as being the momentum space since Reciprocal Space is basically a Fourier transform of the lattice. That only makes sense if X is a wavelength and therefore 2*pi/X * h-bar = momentum. But I don't understand why X would be a wavelength. I guess it would be the maximum wavelength between atoms? And then 2*pi/X * h-bar is the minimum momentum that can get transferred? I am really clueless.