The relation of a particular electron to the nucleus can be described through a series of four numbers, called the Quantum Numbers. The first three describe the energy, shape, and orientation of the orbital. The fourth represents the "spin" of the electron.

The periodic table is a tabular arrangement of chemical elements organized based on their atomic number, electron configuration, and recurring chemical properties. Elements are presented in order of increasing atomic number. States that the atomic weight of the middle element is the arithmetic mean of the other two elements in a triad of elements with similar properties.