# Bosonic Nuclei

**URL:** <https://boards.straightdope.com/t/bosonic-nuclei/315666>\
**Category:** Factual Questions\
**Created:** [August 5, 2005, 2:43am UTC](https://boards.straightdope.com/t/bosonic-nuclei/315666 "2005-08-05T02:43:19Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![randomlyblanks](https://avatars.discourse-cdn.com/v4/letter/r/71c47a/32.png) [@randomlyblanks](https://boards.straightdope.com/u/randomlyblanks)\
**Post date:** [August 5, 2005, 2:43am UTC](https://boards.straightdope.com/t/bosonic-nuclei/315666/1 "2005-08-05T02:43:19Z")

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I’ll basically keep this short: I have a question about bosonic nuclei, and hopefully I’m not overlooking something simple.

A Helium-4 nucleus has 2 protons and 2 neutrons. Each of these particles has a 1/2 integer spin, but as a composite the total spin is an integer so it is a boson.

The question is: why is sodium-23 bosonic and potassium-40 fermionic? Shouldn’t particles with an even mass number be bosonic and particles with an odd mass number fermionic? What am I overlooking here?

Thanks.

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [August 5, 2005, 4:07am UTC](https://boards.straightdope.com/t/bosonic-nuclei/315666/2 "2005-08-05T04:07:01Z")

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I think you have to count the electrons too.  
Bosonic Na 23 has 11 protons, 12 neutrons, and 11 electrons, totalling an even 34.  
[Fermionic K 40](http://physicsweb.org/articles/news/8/1/14/1) has 19 protons, 21 neutrons an 19 electrons, totalling an odd 59.

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**Author:** ![randomlyblanks](https://avatars.discourse-cdn.com/v4/letter/r/71c47a/32.png) [@randomlyblanks](https://boards.straightdope.com/u/randomlyblanks)\
**Post date:** [August 5, 2005, 4:28am UTC](https://boards.straightdope.com/t/bosonic-nuclei/315666/3 "2005-08-05T04:28:43Z")

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> [@Squink](#):
>
> I think you have to count the electrons too.  
> Bosonic Na 23 has 11 protons, 12 neutrons, and 11 electrons, totalling an even 34.  
> [Fermionic K 40](http://physicsweb.org/articles/news/8/1/14/1) has 19 protons, 21 neutrons an 19 electrons, totalling an odd 59.

And that would be what i overlooked. Thanks!

QED

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**Author:** ![Bippy\_the\_Beardless](https://avatars.discourse-cdn.com/v4/letter/b/ac8455/32.png) [@Bippy\_the\_Beardless](https://boards.straightdope.com/u/Bippy_the_Beardless)\
**Post date:** [August 5, 2005, 3:28pm UTC](https://boards.straightdope.com/t/bosonic-nuclei/315666/4 "2005-08-05T15:28:04Z")

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Since there should be equal electrons to protons, wouldn’t just counting the Neutrons and seeing if they were odd or even work just as well?

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**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\
**Post date:** [August 5, 2005, 3:49pm UTC](https://boards.straightdope.com/t/bosonic-nuclei/315666/5 "2005-08-05T15:49:24Z")

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Sure. The periodic table gives you proton number though, so you have to subtract that from the mass to get neutrons. That leaves you with all three particle numbers; unless some wily scientist has removed an electron from your potassium 40, and turned it into a boson. 😉