Radioactivity

[memy]

Hello,

 

This is a question about radioactivity. Basically, nuclei decay since they are unstable in order to achieve the proton to neutron ratio that stable nuclei have.

 

I was just wondering why nuclei that lie above the band of stability ( neutron rich ) are unstable....

 

I know that the nuclei that lie under the band of stability ( proton rich) are unstable since the repulsion between the protons is greater than the strong force and therefore decay by ejecting protons, but in the case of the neutron rich nuclei what makes them unstable?

 

cheers

[swansont]

Hello' date='

 

This is a question about radioactivity. Basically, nuclei decay since they are unstable in order to achieve the proton to neutron ratio that stable nuclei have.

 

I was just wondering why nuclei that lie above the band of stability ( neutron rich ) are unstable....

 

I know that the nuclei that lie under the band of stability ( proton rich) are unstable since the repulsion between the protons is greater than the strong force and therefore decay by ejecting protons, but in the case of the neutron rich nuclei what makes them unstable?

 

cheers[/quote']

 

Neutrons are unstable essentially because being a proton is a lower energy state. In neutron-rich nuclei, there are unoccupied proton states avalaible, so the system can achieve a lower energy by having neutron(s) decay.

[memy]

Why are protons more stable than neutrons?

is it because protons are made of two 'up' quarks with charge 2/3 and one down quark with charge 1/3 while neutrons are made of two down quarks and one up quark? If yes, how this can explain the different stabilities of protons and neutrons?

 

thank you

[RyanJ]

Why are protons more stable than neutrons?

is it because protons are made of two 'up' quarks with charge 2/3 and one down quark with charge 1/3 while neutrons are made of two down quarks and one up quark? If yes' date=' how this can explain the different stabilities of protons and neutrons?

 

thank you[/quote']

 

Have a look here - it should answer your questions

 

Cheers,

 

Ryan Jones

[memy]

So, basically being bigger than the protons ( 1.675 X 10 - 27 kg) , they have more energy ( according to Einsten equation E=MC2) than the protons and therefore they decay into protons.....?

[memy]

So, basically being bigger than the protons ( 1.675 X 10 - 27 kg) , they have more energy ( according to Einsten equation E=MC2) than the protons and therefore they decay into protons.....?

[RyanJ]

So, basically being bigger than the protons ([math]1.675 * 10^{-27}kg[/math]) , they have more energy (according to Einsten equation [math]E = MC^2[/math']) than the protons and therefore they decay into protons.....?

 

Sounds right, in the same way as big things like to become smaler and more stable (Thats why large, unstable nucleii decay into smller and more stable ones)

 

Cheers,

 

Ryan Jones

[swansont]

At a very basic level, protons and neutrons are the same kind of particle, and the proton is at a lower energy state. There's nothing lower that the proton can get to without violating conservation laws. So the proton is stable (or at least if it's unstable it has a lifetime that's large compared to the age of the universe; an implication of this is that whatever conservation law might be broken by its decay has a very slowly changing underlying symmetry)