Octet rule

[MinjooPark_3I]

Hi! So I was doing the sapling workbook problems and realized that for 2E.19, most of the central atoms in this problem did not fulfill the octet rule. Are Be, B, and Sn exceptions to the octet rule or does it only work in this case? Thank you for any help!

[dana hu 1B]

Expectations of breaking the octet rule:
An electron or molecule which contains unpaired electrons in its outermost shell or valence shell is considered as free radical.
Elements like hydrogen, lithium, helium do not obey the octet rule.
Another exception of the octet rule is transition elements. Due to the presence of d-orbitals, they can hold 18 electrons in its outermost shell.
Hope this helps!

[Arnav Saud 2C]

If I'm correct, for this class, the main incomplete octet elements you need to know are Be, B, and Al. The textbook section 2C.3 has a good explanation on the incomplete octet elements as well.

[David Jen 1J]

Hydrogen is also an exception to the octet rule!

[MinjooPark_3I]

Thank you to the people that replied! I will be checking the textbook pages for more info!

[Akshata Kapadne 2K]

Any element from period 3 and onward can have expanded octets because they have d-orbitals that can accommodate additional electrons. Additionally, boron and aluminum have incomplete octets. Lastly, hydrogen, helium, lithium, and beryllium don't have complete octets. I believe those are the only exceptions we have to know. I hope this helps!

[abby hyman]

The exceptions for the octet rule include examples such as SF6 where Sulfur can accommodate more than 8 valence electrons and BCl3 where Boron has less than 8 electrons in its valence shell.

[Arnav Saud 2C]

For the purposes of this class, the p block elements that have an expanded octet are P, S, and Cl. H, He, Li, Be, B, and Al can have an incomplete octet.

[Joshua Chung 2D]

Think of it as the third row p-block elements can have expanded octets, and B, Be, Li, He, and H can have less than an octet.

[Malakai Espinosa 3E]

Some of the elements that don't follow the octet rule are B, Be, and Al.

[Ke Huang 2G]

I was having this question too. Thanks for asking!

[Chenning Yang Dis3l]

Thank you for the post!

[Brandon Carris]

I had this question too thanks for the answers everyone!