Atomic Structural Formulae

[Squidling]

So, I was doing some revision on chemistry, and one of the exam papers that I was practising with had a question on the intermolecular forces between Sulphur and Phosphorus molecules with each in it's own solid state (i.e, comparing Phosphorus's molecular forces with Sulphur's). The only resource that would be allowed in the exam would be an approved data book, and the only information relevant to this question is the valencies that can be found for elements using the periodic table.

 

So, how can you find the normal structure of a molecule of an element with only the valency? I know that you can use valency laws to find some, for example Phosphorus being P4, but elements such as Sulphur have different allotropes, so which one would you take as the "Normal" allotrope in the solid element?

 

Thanks for your time, and sorry if this didn't make a great deal of sense

[Happysedits]

sulphurous is my favourite 

[Professional Map Painter]

https://en.wikipedia.org/wiki/Molecular_orbital_theory

[t0night]

couldn't read question, gif in signature flashed too violently

 

yes this is ironic coming from me

[The Phantom]

So this is kind of a fun question.  What level of chemistry are we dealing with here?  Also, should it be more of a quantitative or qualitative answer?  I hope I can help with this.

[Squidling]

So this is kind of a fun question.  What level of chemistry are we dealing with here?  Also, should it be more of a quantitative or qualitative answer?  I hope I can help with this.

It's Higher (Scottish qualifications), and I'm more looking for a qualitative explanation of why one allotrope is the standard for a solid element. I would guess that it is due to stability, but I haven't been able to find a solid answer as to why one molecule with the same electron configuration would form a completely different molecule as standard (e.g Sulphur and Oxygen are both in group six, and Oxygen is diatomic while Sulphur is not) 

[Squidling]

https://en.wikipedia.org/wiki/Molecular_orbital_theory

I read it over, but this seems to be focusing on the behavior of electrons (which is kind of ignored at the Higher level, unfortunately). I might be missing the point, though; If I gave you the electron configuration of element X, would you be able to tell me what the most stable/normal molecule of that element in it's solid state is? And if not, what other information would you need?

[Hyperqube]

so, basically, why is 'pure' oxigen O2, but is 'pure' sulfer S8?

 

could this help?

[KingPheonix]

... i liek sulphurous. Also why does the forums have a place for stuff like this... .-.

[The Phantom]

Ok, I think I have a more clear understanding of the question now.  Perhaps the most general answer is "Angular Momentum".  From Quantum Mechanics, we see that one of the most commonly referenced observables is the angular momentum of an electron.  I'm positive you're familiar now with electron orbitals and configurations, so that's a good springboard towards the answer.  In fact, the angular "quantum number" (L) is the 2nd of the 4 quantum numbers used to describe electrons.  I think these are typically listed as follows:

 

N - Principle quantum number

L - Angular quantum number (Also Azimuthal quantum number)

M - Magnetic quantum number

S - Spin quantum number (Also M-sub-s, for magnetic spin quantum number)

 

I would consider starting by comparing the valence shell between Phosphorus and Sulfur.  The additional electron that Sulfur possess surely has a major impact.  N will allow you to determine the energy state of the electron, and L allows you to determine the shell (S,P,D,F).  I know that this method of examination is extremely useful when looking at some of the electron configs in the first row of transition metals, so it may help here.

 

I hope this wasn't too far below your skill level, I'm not entirely familiar with what level of chemistry you're at.  I also do not have a major background in chemistry, just to clarify.  I took advanced chem in high school, but I have a solid background in physics and electron behavior, so I'm drawing upon that.  I hope this helped. 

[Squidling]

I hope this helped.

It did, actually; I obviously need to revisit my QM knowledge! Thanks for taking the time to explain, I appreciate it

[Squidling]

could this help?

 

That would indeed be helpful, thanks

[Utsoob]

tfw actual science is posted here instead of some Islamic bs

[Emmy!]

/summon Sugarcube and his science fetishes