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    • #4 - More on the Octet Rule

    The octet rule is really important when it comes to chemistry. You know from the last lesson that atoms want to achieve the lowest energy state possible. That is accomplished when the atom has 8 electrons in it�s outer shell. Naturally, there�s 3 ways to get to 8 electrons.

    1. Lose electrons until the outer shell is empty, and in the process form an ionic bond. Then the "new" outer shell is an inner shell which is full of 8 electrons.

    For example, Sodium has on electron in it�s outer shell, it can combine with a non-metal (chlorine) and get rid of it�s electron and make an ionic bond.
    2. Gain electrons until the outer shell is full, and in the process form an ionic bond
    For example, Chlorine has 7 electrons in it�s outer shell, it can gain one electron from that sodium and create and ionic bond with that sodium
    3. Share electrons (for non-metals only) this is the hardest one, the bonds formed in the process are called covalent or non-metal-non-metal bonds.
    For example, a carbon (C) and two oxygen�s (O) bond to form CO2 and in the process share their electrons ,so all of the elements can experience low energy by having 8 electrons in their outer shell!

    Basically, for atoms to achieve "low energy" they not only have to have 8 in their outer shell, but also bond with one or more atom(s).

    Now, like in every rule of nature, there are exceptions:

    • The octet rule does not apply to hydrogen or helium; they are very small elements and can only fit 2 electrons in their outer shell. They follow the duet rule, they achieve low energy at 2 electrons in their outer shell because that�s all they can fit!
    • Some elements in period 3 and down can violate the octet rule by having more than 8 in their outer shell when they bond with another element. They are called violators. The usual violators are P, S, Cl and the elements below them on the periodic table.
    • Some elements can violate the octet rule by bonding and ending up with fewer than 8 electrons in their shells, the most common of such are Be, and the group 3 elements.

      • This can be quite boring, I know, but you will learn more about this when learning about bonding and that can make it exiting!

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