From what I've heard on this forum the typical nucleus surrounded by protons, electrons and such is not a good representation of an atom.

So what is?

I would like to see a picture, or drawing

The electron orbitals make interesting pictures...

 

http://www.geo.arizona.edu/xtal/nats101/orbitals.jpg

From what I've heard on this forum the typical nucleus surrounded by protons, electrons and such is not a good representation of an atom.

 

Well, perhaps you mistyped, but the nucleus contains the protons (and neutrons) so it's not surrounded by them. The electrons surround the nucleus, but not in anything that looks like a planetary orbit, as Klaynos's link shows.

The uncertainty principle as it relates to wave-particle duality prevents a true pictorial representation of an atom -- at least insofar as "orbiting " electrons are concerned

The uncertainty principle as it relates to wave-particle duality prevents a true pictorial representation of an atom -- at least insofar as "orbiting " electrons are concerned

... because we cannot know exactly where an electron is, electron "orbitals" are pictured as a region in which the electron is most likely to be found.

 

I think the region spans a certain number of standard deviations, usually either 2 or 3, which would result in a respective ~95.5% or ~99.7% probability of finding the electron in that space.

Well, perhaps you mistyped, but the nucleus contains the protons (and neutrons) so it's not surrounded by them. The electrons surround the nucleus, but not in anything that looks like a planetary orbit, as Klaynos's link shows.

 

right right, thats what I meant.

I think what your really asking is what is our most current idesa of what an atom may perhaps look like. We really don't know very well, simply a hypotheesis.

I think what your really asking is what is our most current idesa of what an atom may perhaps look like. We really don't know very well, simply a hypotheesis.

 

The QM descriptions of atomic orbitals have been empirically confirmed. It's definitely not at the level of hypothesis. QM is a well-established theory.

This is what I wanted to know,

thanks

 

this also means the Forum logo is correct

this also means the Forum logo is correct

 

nooooooooooooooooooooooooooooooooooooooooooooooooooooooo!

 

The "orbits" shown by the forum logo (which blike will tell you isn't supposed to be a bohr atom it's just a bit sciencey), looks like a bohr model atom, which has set classical orbits for electrons.

 

This is not true, there are many reasons why this is not true, what would keep the electrons in orbit and not just plummet into the nucleus, and an orbiting charge is accelerating, and accelerating charges radiate energy, so the electrons would spiral inwards...

 

So the electrons don't orbit in a classical way which could look like that.

How about this artist conception of one proton surrounded by one electron:

 

 

(I am guessing the proton in the center is not to scale (should be smaller?))

 

This is not true, there are many reasons why this is not true, what would keep the electrons in orbit and not just plummet into the nucleus, and an orbiting charge is accelerating, and accelerating charges radiate energy, so the electrons would spiral inwards...

 

So the electrons don't orbit in a classical way which could look like that.

 

Well then, how would one draw this?

losfomot's posted image is not bad, the link I give above gives you the orbitals, which are the regions where electrons are most likely to be found...

(I am guessing the proton in the center is not to scale (should be smaller?))

Nucleus diameter is roughly [math]10^{-15}[/math] m, atom diameter around [math]10^{-10}[/math] m. So yes, unless that resolution is a well-disguised 100000x100000 pixels, then the nucleus shouldn't be larger than 1 pixel if you want to keep it in scale.

It truly gives you an impression of empty space doesn't it:rolleyes:!

I always found this website quite good at understanding atomic orbital shapes..

 

http://winter.group.shef.ac.uk/orbitron/

So what about molecules, say DNA models....are they proper graphical represenations?

 

http://education.jlab.org/qa/molecule_01.html

 

A molecule is what you get when any atoms join together.

 

Oh dear, well if we can't see an atom, then presumably we can't see 2 of them:eek:

 

So how many combined atoms does it take to make a molecule visible to humans...?

So how many combined atoms does it take to make a molecule visible to humans...?

 

It depends on the type of microscope and from what it's constructed.

The microscope that I think allows you best to see atoms is Scanning Tunneling Microscope (STM)

The electron orbitals make interesting pictures...

 

http://www.geo.arizona.edu/xtal/nats101/orbitals.jpg

 

It would make an even better picture if it actually told you what the l, m and n actually meant. And also why there are two different colours used in the picture.

 

Otherwise it fails to have any real use or information whatsoever.

The microscope that I think allows you best to see atoms is Scanning Tunneling Microscope (STM)

 

Does the STM also take the photo's/snapshots....?

It would make an even better picture if it actually told you what the l, m and n actually meant. And also why there are two different colours used in the picture.

 

Otherwise it fails to have any real use or information whatsoever.

 

l,m, and n are quantum numbers.

 

n is the principle quantum number, a non zero integer.

l is the angular momentum quantum number (values of 0,1,2,...n-1)

m is the magnetic quantum number (values -l,...-1,0,1,...l)

 

As for the colours I'll guess at to make the images clearer...

 

Does the STM also take the photo's/snapshots....?

 

electron microscopes can take snapshots.

 

I've got some very nice SEM images of photonic crystals I've taken... our (my university) best SEM can see down to a few nm.

 

For something to be 'visible' it has to be larger than the wavelength (normally a couple of times larger) of the particle with which you are probing it. For visible light this is around 550nm.

Couldn't you use x-rays or something and then artificially extend/enlarge/extrapolate the results in proportion?

 

Like using whatever has a wavelength of 110nm and multiplying the result by 5 to make the image visable?

Couldn't you use x-rays or something and then artificially extend/enlarge/extrapolate the results in proportion?

 

Like using whatever has a wavelength of 110nm and multiplying the result by 5 to make the image visable?

 

That's why we use electron microscopes, they have a very short wavelength.

For something to be 'visible' it has to be larger than the wavelength (normally a couple of times larger) of the particle with which you are probing it. For visible light this is around 550nm.

 

Right....so those models of DNA molecules are based on photographs rather than inferences.....cool:cool: