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Exceptions to the Octet Rule
Lewis theory is often correct in its predictions, but exceptions exist. For example, the Lewis structure for NO, which has
- 11 electrons, is:
- It is impossible to write good Lewis structures for molecules with odd numbers of electrons, yet some of these molecules exist in nature. In such cases, we write the best Lewis structure that we can.
- Another significant exception to the octet rule is boron, which tends to form compounds with only 6 electrons around B, rather than 8. For example, BF3 and BH3—both of which exist in nature—lack an octet for B.