Reasoning for Octet Exception

[Ashley Kao 1H]

I understand that Si, P, S, and Cl can all have expanded octets, but what properties allows these specific elements to do so?

[Cassidy Kohlenberger 3D]

As all these elements are located in period 3, they can have expanded octets through using their energetically accessible, low-lying d sub-shell for bonding. This is why period 2 elements cannot have an expanded octet, as they don't have access to the d sub-shell.

[Aliya Jain 2B]

Also, expanded octets can occur in all elements starting period 3 and below!

[sbeall_1C]

Yes, it is because of the presence of the d-orbital in the elements staring in period 3! This d-orbital can accommodate the extra electrons! If you look at the formal charge for the elements you mentioned (Si, P, S, and Cl) you can see that having more than the octet minimizes the formal charge and brings it closer to the stable 0, which helps you recognize when an expanded octet would be beneficial.

[Ashley Kumar 3F]

The d orbital can account for the extra electrons which is why elements from period 3 and beyond can have an expanded octet

[Tyler Angtuaco 1G]

Any element in the third period or below can have an expanded octet because the d-shell exists, and is filled after the ns subshell.

[Kaylee Clarke 1G]

expanded octets occur in period 3 and below but they are most common in phosphorus, sulfur, and chlorine.

[Liliana Aguas 3G]

Only elements from period 3 and beyond can have expanded octets as they can fill up the empty d orbitals that follow higher in energy.

[Caitlin Ciardelli 3E]

Rows three and beyond can have an expanded octet (hold more than 8 electrons) because they have access to the s, p AND d orbitals. Having access the the d orbital allows ten electrons to be used in addition to the octet. Rows 2 and above cannot have an expanded octet because they only utilize s and p. Hope this helps!

[Megan_1F]

Row 3 and beyond can have an expanded octet because it's in the 3rd energy level - S, P, and D blocks.

[Mai V 4L]

Does anyone have a video they think is a good referencce for this topic?

[MKearney_4G]

I know it's probably late but this video does a good job explaining it : https://youtu.be/96L6_IwyHRM

[Brian_Wu_3B]

Are expanded octets more unstable than regular octets?

[Justin Lin 1B]

Row 3 and after that have an expanded octet because it's in the 3rd energy level

[Adrienne Chan 1G]

Are expanded octets more unstable than regular octets?

Yes, they generally are. One example is the free radical like the methyl radical and CFCs.

[Adrienne Chan 1G]

Are expanded octets more unstable than regular octets?

Yes, they generally are. One example is the free radical like the methyl radical and CFCs.

[reva_bajjuri]

do expanded octets usually correspond with resonance lewis structures or are those two things unrelated?

[Alexandra Salata 2L]

do expanded octets usually correspond with resonance lewis structures or are those two things unrelated?

I'm pretty sure they're unrelated:)

[Justin Lin 1B]

The expanded octet can be applied for elements starting from period 3 and below

[Emerald Wong 1B]

The empty d-orbital allows for these elements to have an expanded octet!