[Super Hans (OP)]

Scientists have known the shapes of molecules for centuries, how did they know they are the shape they are when they couldn't see them?
Somebody I asked said it was to do with the number of protons / electrons, but again...how did they know the number when they're too small to view.
I don't understand how they measure it these days, but I find it impossible to understand how they did it way back before computers were around.

So I'm really interested more about how they knew they look the way they do rather than why they take their particular shapes.

Also a follow up question is, do the molecules actually 'look' like they do as they're illustrated.

As I've said before,  I think TNS is an amazing resource and it's such a good thing that people are able to get answers from the enlightened on these subjects,
so thanks in advance.

[PmbPhy]

Scientists have known the shapes of molecules for centuries, how did they know they are the shape they are when they couldn't see them?

By a combination of theory and experiment. I'm not an experimental physicist/chemist so I can't tell you the specifics though.

For example; see http://www2.pvc.maricopa.edu/tutor/chem/chem130/geometry/geom.html