Expanded Octet

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Tiffany Cao 1D
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Expanded Octet

Postby Tiffany Cao 1D » Sun Nov 12, 2017 9:37 pm

What elements can hold less or more than an octet? Do all of their orbitals need to be filled as well when drawing Lewis dot diagrams?

SPandya1F
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Re: Expanded Octet

Postby SPandya1F » Sun Nov 12, 2017 9:40 pm

All elements can hold an octet except for hydrogen. All of the d-block and above can have an expanded octet. For the Lewis dot diagram, all the orbitals do not need to be filled because atoms can have a formal charge.

Justin Bui 2L
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Re: Expanded Octet

Postby Justin Bui 2L » Sun Nov 12, 2017 9:41 pm

I also recall reading somewhere that starting after Phosphorus, since it and the elements in its family/family to the right are large atoms, it is possible for them to have expanded octets as well.

Kathleen Vidanes 1E
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Re: Expanded Octet

Postby Kathleen Vidanes 1E » Sun Nov 12, 2017 9:43 pm

Generally, lighter s- and p- block elements, like Beryllium (Be) and Boron (B) can have less than an octet. Elements that can have more than an octet include: Phosphorus (P), Sulfur (S), and Chlorine (Cl), and all elements that follow them. Depending on the formal charges that each one has once the Lewis Structure is drawn, they may or may not have all of their orbitals filled.

Rachel Formaker 1E
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Re: Expanded Octet

Postby Rachel Formaker 1E » Sun Nov 12, 2017 9:47 pm

The elements that typically have less than an octet are hydrogen, helium, lithium, and beryllium. Boron also may form molecules where it only has 6 electrons.
For expanded octets, any element in period 3 or later with a d-orbital can have an expanded octet. This includes sulfur, phosphorus and chlorine, which, although they do not use their d-orbitals in their ground states, can use these d-orbitals to form bonds.

Nathan Tu 2C
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Re: Expanded Octet

Postby Nathan Tu 2C » Sun Nov 12, 2017 10:18 pm

Any element with an atomic number less than carbon( aka Li, Be, He, B, and H) can have less than an octet. This is because it requires less energy to have just their s orbital filled than to gain an more electrons to get an octet. Group 3 and below non metals like phosphorus can hold an expanded octet because of their d orbitals. Elements like Li, Be, He, and H typically have less than an octet. With Boron, the only way to know if it will have an octet is to check formal charge. The same thing goes for expanded octets. The only way to know is to check formal charge.

Ilan Shavolian 1K
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Re: Expanded Octet

Postby Ilan Shavolian 1K » Mon Nov 13, 2017 1:51 am

just remember quantum numbers. The l value is the allowed orbitals for each atom.


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