1. The problem statement, all variables and given/known data "Mono-energetic electrons are diffracted by a lattice. Their wavelength is shown to be L=0.35nm. What are the energies of the electrons?" 2. Relevant equations E=hf c=hL 3. The attempt at a solution c/L gives 8.566exp17 h=6.626exp-34 I plug them in and get: 5.66exp-19 J The answer is 1184.4 kJ mol -1. So I divide my answer by 1000, and multiply it by Avogadros number. But my answer is nowhere near the actual answer. Where am I going wrong?