The position of an individual electron can be described by the four quantum numbers: n, l, m l , and m s . The Pauli exclusion principle states that electrons cannot possess the same set of quantum numbers. That means it describes whether the part of the electron lies mostly on the x,y, or z axis of the three dimensional grid. The values of the magnetic quantum number are the negative and positive values of l.
When protons, neutrons, and electrons combine to form an atom, some of their mass is converted to energy and is given off (this is the source of energy in nuclear fusion reactions; because the atom cannot be broken down into its fundamental particles unless the energy for the missing mass is supplied from outside it, this energy is called the binding energy of the nucleus).
Another possibility is a carbon with three bonds and a single, unpaired (free radical) electron: in this case, the carbon has a formal charge of zero. (One last possibility is a highly reactive species called a ‘carbene’, in which a carbon has two bonds and one lone pair of electrons, giving it a formal charge of zero.