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Author Topic: What is the structure of the atomic nucleus?  (Read 1951 times)

x0pk1n

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What is the structure of the atomic nucleus?
« on: 18/09/2013 23:51:04 »
So in AS Physics we were looking at the Nucleus and i want to ask something, but it was probably really stupid, so i didn't ask.

So we are all taught that the Nucleus is incredibly small and dense, which is highly positive and you can conclude this from Rutherford experiment with Alpha particle scattering. That the nucleus is positive as only back scattering can happen if it's repulsion. But i thought particles vibrates naturally, so then don't the atoms vibrate, seeing as the Nucleus is highly dense could it not just at certain angles/direction of motion when vibrating scatter it backwards?

Thanks,
(Sorry for the stupid questions or incorrect terminology/not making sense)
« Last Edit: 25/09/2013 19:13:06 by chris »


 

Offline Pmb

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Re: Basic question on Nucleus structure...
« Reply #1 on: 19/09/2013 00:44:34 »
Quote from: x0pk1n
So we are all taught that the Nucleus is incredibly small and dense, which is highly positive …
First off, there is no such term “incredibly small”. Second, there is no need to argue for the fact that both the alpha particle and the nucleus are both small and positively charged. You can assume we all know this by the topic of this forum. This allows us to focus only on what is important and not attempt to sort through poorly phrased qualifying remarks.

Quote from: x0pk1n
But i thought particles vibrates naturally, …
It’s comments like this that require qualification. Why should particles vibrate naturally? (Please note that your comment here really should be stated “But i thought particles vibrate naturally”, there shouldn’t be an “s” at the end of vibrate). What context are you referring to?

Quote from: x0pk1n
, so then don't the atoms vibrate, …
If you’re referring to particles in a potential well having non-zero energy and therefore cannot have zero momentum must vibrate then I agree. However that would be for bound particles only, not free particles in general such as single atoms.

Quote from: x0pk1n
…seeing as the Nucleus is highly dense could it not just at certain angles/direction of motion when vibrating scatter it backwards?
That response is too confusing to address. Please reread and carefully think over before you attempt to rephrase
 

x0pk1n

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Re: Basic question on Nucleus structure...
« Reply #2 on: 19/09/2013 16:15:15 »
Yeah I already said sorry for my stupidity at the end, so thanks for highlighting it!

I was stating facts so you knew where i was at, not for your benefit.

Could you please explain what you said about vibrating particles/atoms again, i didn't understand what you said.

Thanks,
(again sorry for my stupidity)
 

Online alancalverd

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Re: Basic question on Nucleus structure...
« Reply #3 on: 19/09/2013 22:19:01 »
Not too sure what the question is. The Rutherford experiment shows that there must be something small and heavy in the middle of an atom: small because only a small fraction of the incident beam is backscattered and heavy because it scatters a massive particle. And presumably positively charged (or at least not negatively charged) because it scatters a positive particle rather than absorbing it.   
 

Offline Soul Surfer

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Re: Basic question on Nucleus structure...
« Reply #4 on: 19/09/2013 22:20:49 »
I think that PMB is being a bit pedantic in his response to you.

It is true that the interior of any nucleus is a dynamic interacting structure(just like all materials and atoms because nothing is totally static even at absolute zero)  with the protons and neutrons and their internal structured particles the quarks all interacting with each other quite violently.  but the experiment would not detect this aspect of any interaction in any measurable way.

In the case of the Rutherford alpha particle scattering experiments the target was gold with 79 protons and 118 Neutrons and the probe particle helium nuclei with two protons and two neutrons both of which are complex dynamic structures.

The experiment looked at the angle at which each alpha particle was scattered as it passed through an exceedingly thin film for which the approximate density of atoms was known.

The effect of the individual particle dynamics on the scattering could not be determined although it would have had some effect all that could be measured was the probability of the individual particles being deflected and the angle through which they were deflected.  what Rutherford wanted to measure was the size and shape of the individual atoms

In fact most of the alpha particles went straight through the foil without being deflected at all this was because as far as the heavy high energy alpha particles are concerned most of the atom is empty space and the probability of a large deflection by the main mass of the nucleus was low (however some alpha particles even came back close to the direction they were sent this was interpreted as the main mass was the positively charged nucleus with a tenuous cloud of light electrons (which have little effect on the high energy heavy alpha particles) occupying most of the volume that atoms occupy in a solid.
 

Offline yor_on

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Re: Basic question on Nucleus structure...
« Reply #5 on: 21/09/2013 13:35:37 »
I'm losing you at "But i thought particles vibrates naturally, so then don't the atoms vibrate, seeing as the Nucleus is highly dense could it not just at certain angles/direction of motion when vibrating scatter it backwards? "

Are you wondering that if we assume it (a nucleus) a 'solid' of some weird sort, vibrating due to HUP, it would scatter particles differently, depending on where it is in its vibrations? And don't worry about being stupid, I'm there most of the time :)
 

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Re: Basic question on Nucleus structure...
« Reply #5 on: 21/09/2013 13:35:37 »

 

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