Covalent Bonding: O2 vs S8 - Understand the Logic

In summary, the conversation discusses the stability of O2 and S8 molecules and the logic behind their formation. It is noted that S8 has the lowest energy in certain circumstances, but there is no simple explanation for this. Chemistry is seen as a complex and unpredictable science, with many exceptions to rules. The idea of electron correlation and the role of quantum chemistry is also mentioned as a factor in the stability of these molecules.
  • #1
dnorric
4
0
Ok I understand that O2 wants to have a stable number of electrons for its period which is 8 and so it shares two pairs of electrons. But what about S8. I thought it would form S2. Why is it forming S8, what is the logic.
Cheers
Damian
 
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  • #2
I am afraid there is no simple logic behind. For some reasons S8 has the lowest energy in a given circumstances. Quite often that's just the way it is and it is not possible to give a systematic explanation other than "if you calculate the energy of different molecules, there is a minimum here".
 
  • #3
This is why chemistry drives me crazy. There are so many exceptions to the rule, it hardly seems a science in comparison to physics. Thanks heaps for your help though

Borek said:
I am afraid there is no simple logic behind. For some reasons S8 has the lowest energy in a given circumstances. Quite often that's just the way it is and it is not possible to give a systematic explanation other than "if you calculate the energy of different molecules, there is a minimum here".
 
  • #4
dnorric said:
This is why chemistry drives me crazy. There are so many exceptions to the rule, it hardly seems a science in comparison to physics. Thanks heaps for your help though

That's what happens when you study real systems instead of idealized models :p
 
  • #5
dnorric said:
There are so many exceptions to the rule, it hardly seems a science in comparison to physics.

It depends on the selection of the rule. If the rule is "whichever system has the lowest energy, is the one observed in nature", this is not an exception.

But then you can't explain the system in the simple terms like "stable octet"...

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  • #6
I think Mathematics and Physics are the ultimate weapons in dealing with Chemistry...
 
  • #7
Since there are so many exceptions to the rule, perhaps it's just that we have yet to find the true and complete conditions of the rule. Just a thought...
 
  • #8
There are many exceptions because the rule is oversimplified.

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  • #9
There is a logic. Take some classes in quantum chemistry.
In the case of oxigen and sulfur the problem has to do with electron correlation.
Loosely speaking, in Oxigen the electrons are already so densely packed, that O2 tries to avoid contact with other oxigen atoms or molecules and instead develops a very strange double bond. In sulfur the orbitals are so much larger that electronic correlation is not a relevant topic any more. So it forms rather simplistic single bonds. The energetic differences between S4 S6 S8 to S_infinity are rather minute so that it is quite difficult to predict which one is actually most stable.
 

1. What is a covalent bond?

A covalent bond is a type of chemical bond where two atoms share electrons in order to achieve a stable electron configuration. This sharing of electrons allows the atoms to form a molecule.

2. What is the difference between O2 and S8 in terms of covalent bonding?

O2, or oxygen gas, has a double covalent bond between two oxygen atoms. S8, or sulfur, has a single covalent bond between eight sulfur atoms. This means that oxygen molecules have two shared electron pairs, while sulfur molecules have one shared electron pair.

3. How does the number of valence electrons affect covalent bonding?

The number of valence electrons in an atom determines how many bonds it can form. Atoms with fewer than four valence electrons tend to gain electrons to achieve a stable electron configuration, while atoms with more than four valence electrons tend to lose electrons. This allows them to form covalent bonds with other atoms to achieve a stable electron configuration.

4. What is the significance of understanding the logic behind covalent bonding?

Understanding the logic behind covalent bonding allows scientists to predict the types of molecules that can form between different elements. It also helps in understanding the properties and behaviors of these molecules, which is important in fields such as chemistry, biology, and materials science.

5. Can covalent bonds be broken?

Yes, covalent bonds can be broken through either a chemical reaction or physical means. Chemical reactions involve the breaking and forming of covalent bonds, while physical means such as heating or applying pressure can also break covalent bonds. However, the strength of covalent bonds varies depending on the elements involved, so some are more difficult to break than others.

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