Central atom and octet rule?

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Rebecca Chu 1C
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Central atom and octet rule?

Postby Rebecca Chu 1C » Sun May 27, 2018 4:19 pm

Does the central atom have to follow the octet rule? I noticed in some lewis structures the central atom doesn't always have an octet.

Chem_Mod
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Re: Central atom and octet rule?

Postby Chem_Mod » Sun May 27, 2018 4:47 pm

Octet rules will apply except for atoms that can have exceptions.

victoriatanaka1C
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Re: Central atom and octet rule?

Postby victoriatanaka1C » Sun May 27, 2018 4:47 pm

The central atom can have an expanded octet if it appears in Group 3 or below. Their d-orbitals allow for bonding beyond 8 e-. There are also other exceptions to the octect rule, like Group 13 elements, H, He, Li, and Be. The octet rule is a guideline, not a hard fast rule!

yazminedesan1F
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Re: Central atom and octet rule?

Postby yazminedesan1F » Sun May 27, 2018 9:14 pm

it depends on the element usually

Maya Khoury
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Re: Central atom and octet rule?

Postby Maya Khoury » Sun May 27, 2018 9:51 pm

central atoms can have an expanded octet, less than an octet, or an odd number of electrons! an example of the exception with odd number of electrons would be the molecule nitrous oxide (NO) which has 11 total electrons. oxygen would have 6 lone pair electrons plus the single bond electrons, while nitrogen will only have 3 lone pair electrons plus the single bond of electrons. Common examples for elements with less than an octet are Boron and Beryllium. And expanded octets can happen beginning with the n=3 principal quantum number, where the d orbitals become available (l=2)!

Bree Perkins 1E
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Re: Central atom and octet rule?

Postby Bree Perkins 1E » Tue May 29, 2018 8:12 pm

Can elements such as iodine exceed the octet rule? Can it form double and triple bonds even though it has 7 valence e-?

Maria Zamarripa 1L
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Re: Central atom and octet rule?

Postby Maria Zamarripa 1L » Sun Jun 10, 2018 5:30 pm

All atoms have to follow the octet rule unless they are able to have an expanded octet. Elements in period 3 or after are able to hold more than 8 electrons.

Adam Yaptangco 1D
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Re: Central atom and octet rule?

Postby Adam Yaptangco 1D » Sun Jun 10, 2018 6:04 pm

Central atoms can have fewer than 8 atoms or more than 8 atoms depending on the circumstances. If an element has access to d-orbitals (group 3 and beyond), then there can be more than 8 electrons on the central atom.

Amanda 1A
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Re: Central atom and octet rule?

Postby Amanda 1A » Sun Jun 10, 2018 8:48 pm

is there a rule to know when some atoms are okay with having less than 8 electrons? or should we just memorize some of them and hope for the best?

Kara Justeson 1B
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Re: Central atom and octet rule?

Postby Kara Justeson 1B » Sun Jun 10, 2018 9:07 pm

In response to the question above asking when it's ok to have less than 8 electrons, I think you just have to look at the formal charge and see what makes it the closest to neutral. I'm not completely sure though.

Molly Oakes 1A
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Re: Central atom and octet rule?

Postby Molly Oakes 1A » Sun Jun 10, 2018 10:40 pm

Usually, but some elements can have expanded octets. I believe elements after Ne on the periodic table can have expanded octets.

Andrea Raymundo 1B
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Re: Central atom and octet rule?

Postby Andrea Raymundo 1B » Thu Jun 14, 2018 12:58 am

Amanda 1A wrote:is there a rule to know when some atoms are okay with having less than 8 electrons? or should we just memorize some of them and hope for the best?

i think it is just memorization but its basically just group 13 and H, He, Li, Be

John Kim Lec3Dis3L
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Re: Central atom and octet rule?

Postby John Kim Lec3Dis3L » Sat Oct 20, 2018 12:56 am

Andrea Raymundo 1B wrote:
Amanda 1A wrote:is there a rule to know when some atoms are okay with having less than 8 electrons? or should we just memorize some of them and hope for the best?

i think it is just memorization but its basically just group 13 and H, He, Li, Be


This actually showed up in another post I think, and don't quote me on this but the general rule seems to always be group 13 and periods 1 to 3. This, however, is for having less or more electrons than the octet rule.


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