eli5: Why equal number of neutrons and protons in a nucleus result in 0 nuclear spin? I don’t get the explanation online =( thank you in advance!
In: Physics
Protons and neutrons are fermions with half integer spin that obey the Pauli Exclusion Principle. This means they can only have spin values of +-n* 1/2 and no 2 fermions can have the same spin. To minimize energy fermions will take the lowest available spin values. Which is + and which is – is irrelevant so lets just say protons are always spin 1/2 and neutrons are always spin -1/2
Lets look at how this plays out:
|Protons|NEutron|Spin|
:–|:–|:–|
|1|0|1/2|
|0|1|-1/2|
|2|1|1/2|
|2|2|0|
|3|2|1/2|
|4|2|1|
|5|2|3/2|
So as you can see whenever the number of protons and neutrons is equal we get 0 spin. If they are different we get the spin as (#protons – #neutrons)*1/2.
Electrons around neutrons and protons are often stabilized by each other. If you take the electrons away from the nucleus, and put all the electrons in a wire and move all the electrons in the same direction, the negative energy becomes concentrated as the electrons orient themselves in the direction of the wire. That is one way a magnetic field is created.
Neutrons might be neutral but they increase the area of the electrons orbit and distributes the energy over a greater area, this is going to change the rate at which the electron can make the same orbital with the same amount of energy. Since neutrons aren’t charged they aren’t technically considered magnetic by definition but they do spin and have a magnetic effect of their own and are labeled as half spin because they aren’t charged. This doesn’t make sense until you introduce the quark model that says the neutron is made of a positive and negative you can really make it up at this point
This is not true.
From Wikipedia:
* Deuterium (1 proton, 1 neutron): spin 1.
* Lithium-6 (3 protons, 3 neutrons): spin 1.
* Nitrogen-14 (7 protons, 7 neutrons): spin 1.
* Flurine-18 (9 protons, 9 neutrons): spin 1.
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