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The '''Aufbau principle''' is an approximate procedure for writing the ground state electronic configuration of [[atoms]]. The configuration of an atom is obtained by inserting one [[electron]] into the configuration of the atom immediately to its left on the periodic table. The electron is inserted into the subshell indicated by the element's period and block.<ref>http://antoine.frostburg.edu/chem/senese/101/electrons/glossary.shtml</ref>

The '''Aufbau principle''', also known as the ''building-up rule'', is a method for determining the configuration of [[electron|electrons]] in an [[atom]] or [[ion]]. The rule states that the electrons surrounding a nucleus can be "built up" by first occupying the most stable orbitals, often those of the lowest energy level.

==References==

===Example===

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This principle can be illustrated by examining the distribution of electrons in an atom of [[carbon]]. The six electrons surrounding a stable carbon [[nucleus]] would be built up the following way - first, an electron would be added to the 1s orbital. This is the lowest energy orbital and closest to the nucleus. By applying the [[Hund rule]] in conjunction with the Aufbau principle, one can determine that the second molecule will also occupy the 1s orbital. The [[Pauli Exclusion principle]] then yields that any further electrons must be added to the 2s shell. After both the 1s and 2s orbitals are full (for a total of four electrons), electrons may be added to the next highest energy level, the 2p orbital; the two remaining electrons can be found here. This process yields the electron configuration of carbon as ''1s² 2s² 2p²''.

[[Category:Chemistry]]

[[Category:Chemistry]]