Exception to octet rules

[Wendy Phung]

What are some of the exceptions to the octet rule? How do these exceptions affect the structure and stability of molecules containing these exceptions?

[Lily Cornett 1H]

Molecules like BF3 have the central atom, B, that doesn't have a complete octet. Since the central atom is electron deficient and more reactive therefore it is a strong Lewis acid because boron seeks another electron pair to complete its octet. For an expanded octet, like SF6, they have an expanded octet due to the availability of d-orbitals in elements starting from the third period which allow them to accommodate more electrons. They exhibit greater structural complexity and often have more stable and symmetric geometries.