I've read a good few different explanations and learned about electron configurations in school but I still don't understand how to write the electron configuration for a big atom like Copper. Heres how I would write it 1S2,2S2,2P6,3S2,3P6,3D.... First off he told me 3D didn't even belong there. I'm thinking he might mean because the 3D orbital is an exception and actually appears after 4S. I didn't think he'd expect us to know that though he never taught us that. Second thing I don't get is how many electrons go into a D orbital and why D orbitals don't effect the octet rule of chemical bonds. Is it only P orbital electrons that are involved in bonding or something?