Electron Capture: Explaining Too Many Neutrons

[Drizzy]

Homework Statement

My book is saying that if a nucleus has too many neutrons beta minus decay or electron capture is going to happen. The nucleus wants to get rid of a neutron so it is going to send out one electron and an antineutrino that originally comes from the neutron. But what I don't understand is electron capture. The nucleus is going to capture an electron and together with a proton make a neutron. So that means we will have one more neutron than in the beginning. Why does the nucleus make another neutron if it already has too many?

Homework Equations

The Attempt at a Solution

 

[SteamKing]

Homework Statement

My book is saying that if a nucleus has too many neutrons beta minus decay or electron capture is going to happen. The nucleus wants to get rid of a neutron so it is going to send out one electron and an antineutrino that originally comes from the neutron. But what I don't understand is electron capture. The nucleus is going to capture an electron and together with a proton make a neutron. So that means we will have one more neutron than in the beginning. Why does the nucleus make another neutron if it already has too many?

Homework Equations

The Attempt at a Solution

I'm not sure what your textbook is saying, but electron capture is not used to reduce the number of neutrons in a nucleus (I'm not sure what "too many neutrons" even means).

https://en.wikipedia.org/wiki/Electron_capture

Both beta decay and electron capture are processes whereby nuclei try to achieve a better neutron-proton ratio for greater atomic stability.

https://en.wikipedia.org/wiki/Neutron–proton_ratio

 

[Drizzy]

okay I get what you mean but if the ratio is too high( too many neutrons) why does electron capture occur? the ratio is going to get even bigger

 

[SteamKing]

okay I get what you mean but if the ratio is too high( too many neutrons) why does electron capture occur? the ratio is going to get even bigger

Which process occurs depends on how the neutron-proton ratio is originally skewed in the nucleus.

If there are too many neutrons, then there will be a beta decay to convert one of the neutrons to a proton.

If there are too many protons, then electron capture will convert one of the protons to a neutron.

It's not about the absolute numbers of protons and neutrons in the nucleus, but the ratio of neutrons to protons which is a gauge of atomic stability.

 

[Drizzy]

Exactly what i was thinking! if there are "too many" protons electron deccay is going to happen but my book is saying that it happens when there are too many neutrons. I am going to ask my teacher on monday