Basic chemistry: sulphur dioxide shape?

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Discussion Overview

The discussion revolves around the molecular shape of sulfur dioxide (SO2), focusing on its Lewis structure, bond formation, and the concept of resonance. Participants explore the confusion surrounding the valence electrons of sulfur and the nature of the bonds in SO2.

Discussion Character

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

Main Points Raised

  • One participant expresses confusion about how to draw the Lewis structure for SO2 and questions the arrangement of electrons.
  • Another participant states that sulfur has 6 valence electrons and describes the bond as O-S-O with a bond angle of 120 degrees, mentioning a lone pair on sulfur.
  • There is a discussion about the concept of a "partially double bond," with one participant questioning how sharing a pair of electrons can be considered a single bond.
  • A later reply introduces the idea of resonance, suggesting that the double bond can shift between the two oxygen atoms.
  • One participant expresses frustration with the complexity of the topic, indicating that it may be beyond their current level of understanding.
  • Another participant points out a misunderstanding regarding terminology, clarifying the difference between molecules, atoms, and bonds.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding the bonding in SO2, with some confusion about the nature of the bonds and the concept of resonance. There is no consensus on the explanation of the "partially double bond" concept, and disagreements arise over terminology and clarity of expression.

Contextual Notes

Participants mention the complexity of the topic and the potential for misunderstandings related to the definitions of chemical terms. The discussion reflects a range of familiarity with the subject matter, which may affect the clarity of explanations.

hyurnat4
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Basic chemistry: sulphur dioxide shape??!

I realize this isn't homework, but it's so basic I'm ashamed of putting it in the chemistry section. I'm trying to self-teach here, but my textbook is awful and I'm even worse.

Question: Workout the shape of SO2.

Step 1: Draw lewis diagram to work out how lone pairs and bonds are arranged. That's my first problem. I can't figure out how in high heaven the funny dots fits together in a way that works. Resigned, I improvise step 2

Step 2: Go onto wikipedia and discover that SO2 is structured O=S=O. Problem #2. Since when did sulphur get 10 electrons in the valence shell?? Ignoring the lone pair apparently in limbo I finish the question.

Step 3: 2 double bonds → 2 electron clouds → a linear molecule.
Checking the answers, SO2 is bent. Apparently, I should have counted the 5th pair. So ultimately my question is: why does sulphur has 10 electrons in SO2? Very confused here and any help will be appreciated. Thanks in advance.
 
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hyurnat4 said:
So ultimately my question is: why does sulphur has 10 electrons in SO2? Very confused here and any help will be appreciated. Thanks in advance.

Sulphur has 6 valence electrons. The bond formed is O-S-O where the angle OSO is 120 degree.
In this structure, sulphure shares a pair of electrons with oxygen. This bond is partially double bond. The bond length is 143 pm which comes between single and double bond length(due to resonance)
The concept is bit too high.
Simply see it as, sulphur has 1 lone pairs in this bond.
 


rktpro said:
Sulphur has 6 valence electrons. The bond formed is O-S-O where the angle OSO is 120 degree.
In this structure, sulphur shares a pair of electrons with oxygen. This bond is partially double bond.

Still trying to get my head round this... I don't get the 'partially double bond' bit. Isn't sharing a pair of electrons by definition a single bond?
Thanks for the reply.
 


hyurnat4 said:
Still trying to get my head round this... I don't get the 'partially double bond' bit. Isn't sharing a pair of electrons by definition a single bond?
Thanks for the reply.
Partial double means that the double bond can shift between the two oxygen molecules.
Resonance[/PLAIN]
 
Last edited by a moderator:


rktpro said:
double bond can shift between the two oxygen molecules

You might want to correct it.
 


Oh...
That seems... unfair. Why does chemistry have to be more complicated than it already is?
Thanks for the help anyway guys, this is probably a bit beyond what I'm supposed to learn but it's good to know how the molecule works. :frown:
 


Sorry, Borek.
IT shifts between one oxygen molecule and sulphur molecule pair to the other oxygen and sulphur molecule pair where sulphur is common to both.
 
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I understand English is not your first language? Please check exact meaning of the words molecule, atom and bond - what you wrote makes no sense. Oxygen molecule is O2. I guess you mean electrons move between oxygen-sulfur bonds inside the SO2 molecule.
 

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