Princiapl quantum number, n: an integer that represents, and can be used to calculate, the total energy of an electron in an atom. Its values are n = 1,2,3,...
Spin quantum number,s: a quantum number that repreents a property of an electron which is likened to spin.
electron configuration: an arrangement of electrons in a sequence of atomic orbitals starting with the lowest energy orbital.
Aufbau principle: a rule that states that electrons in unexcited atoms are distributed within the levels using the lowest energy orbital first, the next lowest second, and so on.
Hund's rule: when placing electrons into a set of equivalent orbitals, each orbital receives one electron before any orbital is given two.
Pauli exclusion principle: no two electrons in an atom can have all four of their quantum numbers exactly the same.