## Expanded Octet

BKoh_2E
Posts: 87
Joined: Wed Sep 30, 2020 9:57 pm

### Expanded Octet

Can anybody explain which elements can have an expanded octet? In lecture he mentioned something about the d-block, but I didn't really understand.

Posts: 153
Joined: Wed Sep 30, 2020 9:32 pm
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### Re: Expanded Octet

Any element that exists in 3p orbitals or greater can have an expanded octet. This is because there is an unoccupied d orbital which can be used for bonding. Si, P, Cl, and S are all common examples of elements that can have expanded octets (as they all have electrons in the 3p state). Additionally, elements such as Se (with an electron in the 4p state) can also have an expanded octet, but I think for this class we will only be creating Lewis structures with elements up until n=3.

Hope this helps!

manisha_joseph_1H
Posts: 87
Joined: Wed Sep 30, 2020 10:01 pm

### Re: Expanded Octet

I believe elements can have an expanded octet when they are located in row 3 or lower on the periodic table, as they have that additional d-orbital in their valence shell that can accommodate more electrons (resulting in more than 8 valence electrons). Hope that helps!

Jack_Pearce_2H
Posts: 93
Joined: Wed Sep 30, 2020 9:48 pm

### Re: Expanded Octet

should be the third period down. But honestly it depends on which element youre talking about because some are specifically expanded octets and others aren't

Marco Morales 2G
Posts: 79
Joined: Wed Sep 30, 2020 10:04 pm

### Re: Expanded Octet

He said in lecture today that the elements from the 3rd period and down have the expanded octet. But then again, he said we'll generally only be focusing on the first three periods of the periodic table for the class because they're more widely used. So I wouldn't really worry about further periods.

Nandhini Ekambaram 1L
Posts: 100
Joined: Wed Sep 30, 2020 9:58 pm

### Re: Expanded Octet

During a step-up session, the UA told us to know P, S, and Cl as the exceptions to the Octet rule. There are definitely more elements that are exceptions, but for this class these three are the only ones we need to know.

Ravdeep Warar 2G
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Joined: Wed Sep 30, 2020 9:36 pm
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### Re: Expanded Octet

Yes, previously in high school chemistry it was important to know that P, S, and Cl are exceptions. I'm not sure how many more there are, but like others have mentioned above, I do not think we will need to know all of them, just the commonly used ones.