<P> The octet rule is a chemical rule of thumb that reflects observation that atoms of main - group elements tend to combine in such a way that each atom has eight electrons in its valence shell , giving it the same electron configuration as a noble gas . The rule is especially applicable to carbon , nitrogen , oxygen , and the halogens , but also to metals such as sodium or magnesium . </P>
the octet rule states that chemical compounds tend to form so that each atom
has eight electrons in its valence shell , giving it the same electron configuration as a noble gas