Change in Mass during ionization

[sanguinee]

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Does mass change when something ionizes? I wrote it down somewhere in my notes but I don't understand why it doesn't change and didn't find any support for on the internet either.

Any help would be very much appreciated!

 

[Cawolf]

Not significantly enough to matter.

When an electron is released, the mass lost is roughly 9.1 x 10^-31 kg.

Compared to the mass of a proton, this is roughly 10^4 smaller.

So the mass lost isn't significant enough to be statistically significant for most purposes.

 

[sanguinee]

Okay, that's what I thought. Thanks @Cawolf

 

[sazerac]

An electron weighs 1/2000 as much as a proton. So if you lost two electrons, you would change the weight 3 positions past the decimal point. You wouldn't even notice...

...or would you? Go check out a periodic table sometime. There are a few elements whose atomic mass is known to an absurd number of places past the decimal. Manganese (Mn, element 25) is usually one of them. If Mn ionizes, which it often does in many different ways, it would affect the atomic mass listed.

It wouldn't affect your calculations much, since surely some other measured value isn't known to 6 significant figures, but I have always thought this was an interesting bit of trivia!