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11/6/2020 Breaking the octet rule Odd electron Some compounds have atoms with more or less than 8 electrons Although rare, it is possible to have compounds that have an odd Lewis dot structures with atoms that break the around them (breaking the octet rule) number of electrons. octet rule There are 3 types Obviously it is not possible to satisfy the octet rule with an odd 1. odd numbered electrons number of electrons, ONE CANNOT BE A PAIR! 2. electron deficient compounds Two compounds are NO and NO2 3. expanded valence shells They will have a free electron on N. Lewis dot Electron deficient compounds This is rare. It is only found Boron, Beryllium or Aluminum The formal charge is appropriate for each atom and compounds. All are highly reactive. the molecule Beryllium, aluminum are a metals, however, since its valence shell Compounds with a free electron, unpaired electron, is so close to the nucleus it can form covalent bonds (rarely). are called free radicals. All atoms are electron deficient (have less than 4 electrons), and They are highly reactive. therefore when they form bonds they can’t make it all the way up These two compounds are used in nitrous oxide to 8 electrons systems in cars Expanded valance shells Examples Examples One atom will have more than 8 valence electrons. This requires a highly electronegative atoms (fluorine, oxygen, or Bl3 PF5 chlorine) to bond with a nonmetal with its outer shell 3 p or higher. The BeH XeF 2 extra electrons can use the unused d orbital. 4 ClF Only the central atom will have more than 8 electrons. 5 PO 3- C, N, O, F and Ne can’t have more than 8 electrons. There is no 2 d 4 2- orbital so there is nowhere to put the extra electrons. SO3 2- All nonmetals underneath them on the periodic table do have an used d SO4 orbital for the electrons. 1.

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