Why isn't Sulphur a diatomic molecule?

I got surprised when trying to form a reaction of sulphuric acid when I came to discover that sulphur is actually a monatomic molecule. If you look in its Group, that being Group 6 (VI), you see that at the top is good old oxygen, and I know for a fact that it is a diatomic molecule as:... show more I got surprised when trying to form a reaction of sulphuric acid when I came to discover that sulphur is actually a monatomic molecule.

If you look in its Group, that being Group 6 (VI), you see that at the top is good old oxygen, and I know for a fact that it is a diatomic molecule as: http://www.healthchecksystems.com/images...

Then why is sulphur subjected to being a loner then? When it is clearly in the correct "place"!

Has it got to do with its outer shells? Or is there a mistake I have spotted and no-one else has.

I'd appreciate a really good answer from you, if you are reading this.

Thanks.
Update: Some guy said that the hint can be found in H2SO4, but thats not really true because even though I understand what he's going on about, we can still form half-moles - can't we?
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