Expanded Valence Shells

[Tracy Tran 3L]

I don't really understand the concept of expanded valence shells. In the case of phosphorus, its electron configuration is [Ne] 3s² 3p³. I don't see how it could have an empty d-orbital

[AlexandriaHunt2J]

Hi! You're right that Phosphorus has the electron configuration of [Ne] 3s² 3p³ in its ground state. However, because Phosphorus exists in the n=3 shell, this means its l values are 0, 1, and 2, which correspond to the subshells s, p, and d respectively. In its ground state, Phosphorus valence electrons exist in the lowest energy state and fill the 3s and 3p orbitals. They do not exist in the 3d orbital because that is of a higher energy state - but this doesn't mean the 3d orbital doesn't exist. The 3d orbital exists, but it just isn't occupied with electrons - which is why Phosphorus can have an expanded valence shell and allow electrons to fill this orbital. Hope this helped!

[Matthew Li 1B]

its is ground state, phosphorus only has 5 valence electrons. however, when it is bonded to other elements it doesn't necessarily abide by the octet rule as it has 10 electrons (an additional 5 electrons from it being shared by Cl) in PCl5. so it would have 2 electrons in the 3d state.

[405716590]

Since there are 5 valence e-, 2 can exist in the d state

[Maeve Settle 2B]

Hey! Basically since phosphorous is in the n= 3 state it has empty d-orbitals that are simply not filled in the lone atom. However, they are still present due to the quantum number l which is 0, 1, and 2 for n=3. Since l=2 corresponds to the d-orbital, these orbitals do exist on the P atom, even if they're not in use. So during chemical bonding n=3 (and higher) atoms can take on more than 8 electrons and maintain an expanded octet, breaking the octet guideline.

[Ruiyu Li 3I]

The electron configuration you mentioned is for ground state phosphorous. Phosphorous is in period 3, which means n=3, l=0,1,2. Thus, it can have d orbitals, which will be used to accommodate additional e- when s and p orbitals are full.