molecules

[Danlad]

I seem to remember back at school when learning about molecules that they are in fact a theory and cannot be proved as they cannot be seen. Whoevers theory it was defined their workings by comparing them to snookerballs. Because everyone knows about molecules I think people will think its common sense that they exist without actually looking into it. People also get confused between atoms and molecules which are 2 seperate entities. Could someone please tell me if I am talking Boll*cks?

[fingerpie]

You are talking Boll*cks

[101325]

The theory you are probably thinking of is "Brownian Motion" and this is actually the motion of smoke particles bouncing around because they have been hit by smaller gas molecules.

An atom is a single particle, the smallest bit of an element, a molecule is a collection of atoms bound together.

[Clanad]

Actually, the atom is not the smallest "part of the element".  The atom is made up of (theoretically) neutrons and protons.  The recent Nobel Prize in Physics was awarded to some folks for research in this area.  I'm not sure, but I believe some electron microscopes have either "seen" larger molecules or at least their "shadows"...

[greenday]

There are now some electron microscopes that can see atoms. Therefore they do exist. If the don't, then I've just wasted the last 8 years.

[New Forester]

Clanad -

 

You are right that an atom is not the smallest thing which forms part of  "an element".  However, I think 101325 was really correct -- it is the smallest thing which can be assigned exclusively to a particular element -- all the smaller bits and pieces occur in other elements just as much.  If you chop an atom up any smaller it becomes something else.

 

Danlad -

 

I think molecular theory is pretty much proved by now, long before anyone seeing a molecule or atom.  Clanad is right that electron tunnelling microscopes can now resolve molecules and even larger atoms -- and x-ray diffraction also shows their shapes and sizes indirectly.

 

There are lots of solidly accepted scientific theories about things which you can't see, or which you can see but can't touch.  No-one, for example, doubts that the sun is a ball of hot stuff 90-odd million miles from us.

 

[fergusq]

Electron microscopes can see atoms - it has been proven that atoms and molecules exist. Also it has been proven that the proton, neutron and electron exist. They do have subparticles (quarks) which can be detected by their paths through electromagnetic fields.

[helghast]

of course atoms exist other wise we wouldn't be able to have nukes. they are made by smashing atoms into each other or spliting them and then harnessing the energy aren't they?