What is a valence shell

Octet rule

Synonyms: noble gas control, eight-electron rule
English: octet rule

1 definition

The Octet rule is a rule from chemistry. It says that atoms with an atomic number below 20 strive for an electron configuration in which the outer shell (valence shell) contains exactly eight electrons. The atoms therefore strive to adopt a noble gas configuration.

2 background

Atoms go chemical bonds a, e.g., metallic bonds, ionic bonds or atomic bonds, thereby forming molecules. The tendency to take these bonds is related to the number of valence electrons. The reactivity of an atom depends on the desire to achieve the maximum number of electrons in the outer shell. When the valence (an atom by the binding of a noble gas configuration s2p6), this arrangement is energetically favorable and particularly stable.

The octet rule is the reason why noble gases have a low tendency to form bonds with one another or with other atoms. They are atomic. Most of the other elements try to arrange themselves with one or more binding partners in such a way that the noble gas configuration (1s2 or S2p6) Is achieved on the outer shell.

The Octet rule states: It is the aim of atoms to come to eight valence in forming a chemical bond.