closer energy level has electrons that have a stronger attraction to the nucleus
to move from level to level, an atom must gain or loose a quantum of energy
7 energy levels & 4 sublevels= s, p, d, f
1= s orbital, 2= s, p orbitals, 3= s, p, d, orbitals, 4-7= s, p, d, f orbitals
electrons in the same orbital must have opposite spins
electrons occupy empty orbitals first