importance of conservation laws in chadwicks discovery of the neutron (1 Viewer)

[allstarr69]

Im not sure how to answer this dot point and this is all I know about it:
Chadwick used the conservation laws to show an interaction between the neutron and a proton in order to calculate the approximate mass for the neutron.

I have no idea how he did this, but is this all you need to know for this dot point?

thanks

 

[Jase]

Basically yes.

But usually that question is linked with bigger questions... so you need to know ALL about the prediction and discovery of particles.
Like -> in 1920 rutherford predict -> 1930, Bothe and Becker found random radiation -> Chadwick's experiment - parrafin, knock proton, detect... blah.. use convservation.. blah.. found it.

 

[allstarr69]

yuk... i dont know any of that lol.. better get to some study!!

 

[gordo]

its more that by the conservation of energy, b/c a proton was knocked out of the parafin by a particle emmited out of the berylium, that particle couldn;t be a gamma ray as suggested because it didn't have that much energy. so by conservation of energy the particle emited out of the berylium must have been a bigger, more massive particle (approx 1.05 times the mass of a proton)...thus neutron arrives

 

[smallcattle]

was Rutherford the first person to predict the existence of neutrons, and Chadwick who first discovered it??

 

[gordo]

rutherford proposed the idea of the neutron
bothe and becker did the experiment to prove it

 

[Constip8edSkunk]

bothe and becker did not prove it...

rutherford predicted the neutron's existence due to discrepencies in calculations of masses
bothe & becker discovered some unknown radiation, thought then to be some extreme gamma radiations in the 20s
fredrick joliet and irene jolietcurie decided to put paraffin in the way of the radiations and found it knocked out protons
chadwick used conservation of energy and momentum to deduce the neutron's existence and its properties

 

[nit]

chadwick substituted the paraffin for nitrogen nuclei, and noted that ll the nuclei he used recoiled in much the same way, with the heavier nuclei recoiling more slowly than the lighter ones. This all pointed towards the fact that the collision was that between two masses, and thus that the unknown thing was a p;article, not radiation as was intially supposed. Then he used conservation of momentum and kinetic energy and the results for the nitrogen test and the paraffin test to determine the mass of the neutron. You can give equations he used if you want, depending on the number of marks allocated for the question.