Octet+Rule

__**Octet Rule**__ By Ethan Bennis

The most stable elements on the periodic table are the Noble Gases. The reason for their stability is that their valence shell is completely filled with 8 electrons. That means that they are extremely nonreactive with other elements. Atoms will naturally try to achieve this same level of stability through gaining, losing, or sharing electrons with other atoms to attain a filled valence shell. Usually this means 8 valence electrons, hence the name "//oct//et rule". These 8 electrons make up a filled s and p subshell, and can also be considered simply to be four outer pairs of electrons. Helium is an exception to the octet rule, as its outer shell consists of just 2 electrons in the 1s subshell. There are also other exceptions, such as free-radicals, but the most notable exceptions are the transition and heavy metals, for which the octet rule often does not apply due to their stability with a half-filled d or f subshell.

Example of a reaction between magnesium and oxygen, as well as a reaction between magnesium and nitrogen: (The rule provides much benefit when drawing lewis dot diagrams.)

Pictures: [|http://www.elmhurst.edu/~chm/vchembook/143mgoxide.html] //Chemistry: The Central Science// (9th Edition)
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