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5.3.1: The Octet Rule

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    The Octet Rule

    The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence shell. When atoms have fewer than eight electrons, they tend to react and form more stable compounds. Atoms will react to get in the most stable state possible. A complete octet is very stable because all orbitals will be full.

    In the formation of covalent bonds, atoms share electrons in order to achieve an octet.

    Octet Rule

    A stable arrangement is attended when the atom is surrounded by eight electrons. This octet can be made up by own electrons and some electrons which are shared. Thus, an atom continues to form bonds until an octet of electrons is made. This is known as octet rule by Lewis.

    1. Normally two electrons pairs up and forms a bond, e.g., \(H_2\)
    2. For most atoms there will be a maximum of eight electrons in the valence shell (octet structure), e.g., \(CH_4\)
    1.png
    Figure 1: Bonding in \(H_2\) and methane (\(CH_4\))
    The other tendency of atoms is to maintain a neutral charge. Only the noble gases (the elements on the right-most column of the periodic table) have zero charge with filled valence octets. All of the other elements have a charge when they have eight electrons all to themselves. The result of these two guiding principles is the explanation for much of the reactivity and bonding that is observed within atoms: atoms seek to share electrons in a way that minimizes charge while fulfilling an octet in the valence shell.

    The noble gases rarely form compounds. They have the most stable configuration (full octet, no charge), so they have no reason to react and change their configuration. All other elements attempt to gain, lose, or share electrons to achieve a noble gas configuration.

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    5.3.1: The Octet Rule is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.