Is XeF4 violating the octet rule?

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Discussion Overview

The discussion centers around the octet rule and its applicability to various chemical species, particularly focusing on xenon tetrafluoride (XeF4) and other molecules like superoxide (O2), sulfur (S8), and boranes. Participants explore whether certain elements and compounds adhere to or violate the octet rule, considering theoretical and structural aspects.

Discussion Character

  • Debate/contested
  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants note that beryllium and boron can bond with fewer than eight electrons, suggesting that exceptions to the octet rule exist.
  • There is a discussion about the superoxide radical (O2), with some participants asserting that it can be represented without violating the octet rule in certain resonance structures.
  • Participants question the stability of octet configurations, referencing quantum calculations that indicate potential energy minima associated with filled subshells.
  • Scott raises the question of S8, with others noting that it is a ring structure and does not violate the octet rule.
  • There is a query about why oxygen does not form O8, with a suggestion that steric strain plays a role in the stability of larger atoms like sulfur in ring structures.
  • Some participants propose that XeF4 may or may not follow the octet rule, inviting others to analyze its electron structure.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the applicability of the octet rule to various compounds. There is no consensus on whether XeF4 adheres to the octet rule, and the discussion remains unresolved on several points.

Contextual Notes

Some claims depend on specific definitions and assumptions regarding electron configurations and bonding, which are not universally agreed upon. The discussion includes unresolved mathematical steps and varying interpretations of molecular structures.

scott_alexsk
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Is there any violation of the octet rule in the second period elements?
-scott
 
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Yes, beryllium typically bonds with 4 electrons (ie BeF2) and boron with 6 (BF3). Flourine is often involved in bonds that have more than 8 electrons (XeF4).
 
Also the superoxide radical, O2 with an extra electron. It's found in biological systems.
 
movies said:
Also the superoxide radical, O2 with an extra electron. It's found in biological systems.

Just to add, this is a biradical, with an unpaired electron on each oxygen atom.

~H
 
Hootenanny said:
Just to add, this is a biradical, with an unpaired electron on each oxygen atom.

~H

You mean singlet oxygen? That's different. In that case you haven't added an electron, in superoxide you have one more electron than you do in the regular oxygen molecule.

Anyway, I think that I was wrong. You can draw a Lewis structure for superoxide radical where you have 3 lone pairs on one O and two lone pairs plus one electron on the other, with a bond between the two. In that resonance structure it's not an octet rule violation. My mistake.
 
What about S8?
-scott
 
scott_alexsk said:
What about S8?
-scott

S is in the 3rd period...

Also, S8 is a ring of sulfur atoms, so there is no violation.
 
Why is octet configuration stable?
 
It just is.

Careful quantum calculations show that there is a deep local minimum of the potential energy for filled ns and np subshells. There are also shallow local minima at half-filled subshells. These are just the results of very complex calculations and it's hard to simplify things - in my opinion - to any considerable extent without being "a little" dishonest.
 
Last edited:
  • #10
Nitrogen does interesting stuff as well - like in hydrazine
 
  • #11
Gokul43201 said:
It just is.

Careful quantum calculations show that there is a deep local minimum of the potential energy for filled ns and np subshells. There are also shallow local minima at half-filled subshells. These are just the results of very complex calculations and it's hard to simplify things - in my opinion - to any considerable extent without being "a little" dishonest.
thanks Gokul
I would request you to explain the difference between a wave and a particle? How would you describe the behaviour of an electron as a wave(qualitatively)?
 
  • #12
Malay, this question is fairly unrelated to the rest of this thread.

I have a couple of suggestions for you.

1. Read post #3 in the Physics FAQ thread : https://www.physicsforums.com/showthread.php?t=104715
It does not directly answer your question, but addresses some part of it.

2. If you still have something you want to ask, start a new thread in the appropriate Physics subforum - General Physics will work - and ask your question there.
 
  • #13
Gokul43201 said:
Malay, this question is fairly unrelated to the rest of this thread.

I have a couple of suggestions for you.

1. Read post #3 in the Physics FAQ thread : https://www.physicsforums.com/showthread.php?t=104715
It does not directly answer your question, but addresses some part of it.

2. If you still have something you want to ask, start a new thread in the appropriate Physics subforum - General Physics will work - and ask your question there.
Thanks for your help
 
  • #14
Why does oxygen not form o8, since it is in the same family as sulfur?Also what about the Boranes?
 
  • #15
One reason is the steric strain. Larger atoms like S, Se, Te can more easily accommodate non-ideal bond angles that are necessary to make the ring structures.

What about the boranes? Yes, they do not satisfy octets in general (see post#2, by cesium). Also look into Wade's rules for constructing boranes with n electron pairs.
 
  • #16
Does that mean that XeF4 follows the octet rule?
 
  • #17
try and draw out the structure of XeF4 and count the electrons. If you draw the correct structure your question should be answered.
 

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