What is n in 4n+2? I understand that it is an integer but what number does it represent? Principal Quantum number? (No, it comes from the mathematical definition of an odd number of orbitals (2n+1). - GS). It is still not clear. (Each orbitals holds 2 electron, so the number of electrons = 2X(2n+1) - 4n+2. - GS).