Which molecule most likely to deviate from ideal values?

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Discussion Overview

The discussion revolves around the factors that cause bond angles in molecules to deviate from ideal values, exploring concepts related to molecular geometry, lone pairs, and polarity. Participants are examining specific molecules and their characteristics in relation to the VSEPR theory.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about the causes of bond angle deviations from ideal values.
  • Another suggests that any factor breaking symmetry, such as using different isotopes, could influence deviations.
  • A question is raised about the connection between polarity and bond angle deviations.
  • Participants discuss comparing different molecules, such as BrCl3, XeCl4, and CO, to determine which deviates the most from ideal values.
  • There is a suggestion that the number of lone pairs on the central atom might correlate with deviation, though confusion arises regarding the specific counts for XeCl4 and BrCl3.
  • Clarifications are sought regarding the ideal bond angles for the mentioned molecules and the role of lone pairs in affecting these angles.
  • One participant expresses that they consider VSEPR theory to define "ideal" values for bond angles.
  • Discussion includes the placement of lone pairs and their impact on molecular geometry, with references to pair repulsion effects.

Areas of Agreement / Disagreement

Participants express varying views on the factors influencing bond angle deviations, with no consensus reached on the specific contributions of lone pairs, polarity, or symmetry breaking. Confusion remains regarding the counts and effects of lone pairs in certain molecules.

Contextual Notes

Some assumptions about ideal bond angles and the definitions of symmetry and polarity are not fully articulated, leading to ambiguity in the discussion. The role of lone pairs and their placement is also a point of contention.

LegitSci
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Hi,

Hoping I could get some help on this one.
How would I know what causes bond angles to deviate from the ideal values?

I greatly appreciate any help and advice on this.

Thanks
 
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Anything that breaks the symmetry; 35Cl instead of 36 in a CCl4 molecule; you name it.
 
Is there any connection between polarity?
 
LegitSci said:
polarity?
Bystander said:
You name it.
 
If so, how would you compare between different molecules? Like if I were to compare which molecules deviated THE MOST from the "ideal" values...
for example BrCl3, XeCl4, or CO
 
does deviation correspond to the number of lone pairs on the central atom, but even then XeCl4 and BrCl3 both have 2 pairs so I'm super confused.
Or does it have to do with location of the lone pairs?
 
LegitSci said:
bond angles
CO? A straight line is a straight line. What are the "ideal" values for the other two? Which isotopes/isotope combinations are you considering "ideal?"
LegitSci said:
XeCl4 and BrCl3 both have 2 pairs
Two pairs? What are you counting?
 
but arent there lone pairs of electrons for central atom (either C or O) CO or do they not affect the bond angles?

for XeCl4 and BrCl3, I am counting the number of lone pairs of electrons.
so there would be 2 pairs of lone pairs on the central atom (Xe and Br, respectively), right?
 
I am considering the VSEPR to be "ideal", sorry for any confusion
 
  • #10
I think I got it. It has to do with the placement of lone pair of electrons on the central atom.

Thanks
 
  • #11
LegitSci said:
central atom (either C or O) CO
One bond can NOT make an angle.
LegitSci said:
would be 2 pairs of lone pairs on the central atom (Xe and Br, respectively)
Yes.
LegitSci said:
VSEPR
So, that's back in fashion --- two pairs --- one on one side and the other opposite --- "pair repulsion" --- what are your thoughts?
 
  • #12
LegitSci said:
I think I got it. It has to do with the placement of lone pair of electrons on the central atom.
Yes --- You're welcome.
 

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