I"m learning exactly how to attract Lewis diagrams. Everything I"ve check out emphasizes the octet rule. However, to the best of mine knowledge, that preeminence only applies to elements in the first three periods.

On our exam, I intend our professor will ask us to attract some Lewis diagrams the molecules whose atoms execute not comport through the octet rule. However, ns haven"t seen any type of diagrams that these; it"d be helpful to get a sense of what castle look choose so the my gut doesn"t reject of what will certainly otherwise be strange spring diagrams.

What room some reasonably common molecule that consist of atoms that make up a an excellent number of valence electrons?

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There space 3 types the octet rule "violations" or exceptions

molecules through an odd number that electrons, such together nitric oxide


(image source)

molecules with less than 8 electrons roughly an atom, $ceBeCl2$ and $ceBH3$ offer as examples


(image source)

molecules through more than 8 electrons approximately an atom, such together $cePCl5$ or $ceSF6$


Take a look in ~ the image resource links for various other examples as well as some exercise problems.

The bonding around electron deficient atoms such together the boron in $ceBH3$ is best explained in terms of 3-center 2-electron binding (reference; SE Chem example_1, SE Chem example_2)).

Sometimes, disagreements based top top d-orbital involvement are advanced to define the bonding in atoms surrounded by more than 8 electrons. Yet d-orbital joining in non-transition metals is now generally considered to it is in unlikely. Instead hypercoordinated (or hypervalent) bonding in which 3-center 4-electron binding are formed has become a an ext generally welcomed explanation. A variety of examples have previously been disputed here on SE Chem (for example, watch here).