The octet rule is a chemical rule of thumb that states that atoms of low (<20) atomic number tend to combine in such a way that they each have eight electrons in their valence shells, giving them the same electronic configuration as a noble gas. The rule is applicable to the main-group elements, especially carbon, nitrogen, oxygen, and the halogens, but also to metals such as sodium or magnesium.
The valence electrons can be counted using a Lewis electron dot diagram as shown at right for carbon dioxide. The electrons shared by the two atoms in a covalent bond are counted twice. In carbon dioxide each oxygen shares four electrons with the central carbon, and these four electrons are counted in both the carbon octet and the oxygen octet.
Other articles related to "octet rule, rule, octet, octets":
... bond angles, bond lengths and apparent violation of the Lewis octet rule, several alternative models have been proposed ... Additional modifications to the octet rule have been attempted to involve ionic characteristics in hypervalent bonding ... This model in which the octet rule is preserved was also advocated by Musher ...
... The duet rule of the first shell - the noble gas helium has two electrons in its outer shell, which is very stable ... These molecules often react so as to complete their octet trivalent boron compounds are well known as Lewis acids which form a fourth bond with a Lewis base, and carbenes are even more reactive ... and aluminium can also have incomplete octets ...
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