Expanded Valence Shells

[Amina Durrani 3G]

How exactly do expanded valence shells work, since the octet rule says that atoms share electrons until a noble gas configuration is reached?

[AngieGarcia_4F]

When atoms have d shells they can hold more than 8 electrons

[Chris Tai 1B]

For instance, an atom like Phosphorus can hold more electrons than just the octet that it gets, since it would fill up its 3p shell, next moving onto the 3d and the 4s shells. Phosphorus can do this because it is in the 3rd period of the table. This is much more difficult for atoms that are in a lower period of the periodic table (period 1, or period 2 etc.)

[Aarja Pavade 1H]

The octet guideline refers to 8 electrons. This gives us the configuration of s2p6. For atoms in Period 3 or higher, their n (principal quantum number) is 3. This gives us an l of 0,1,2, meaning that they have an s,p,and d orbital. The d-orbitals allow Period 3 and higher elements to accommodate the additional electrons.