I am sorry but I still don't understand.
My dictionary said natuurkunde is physics btw.
The unit for mass is the kilogram right? According to the SI?
So mass can be expressed as a number of kilograms.
I would think that if an atom jiggles more it is having a bigger volume. And because of that a lower density. Less kilograms per meter^3. But a change in mass???
I just reread what you posted earlier and I read that an electron is a massless particle? That is new to me as well. The combination particle and massless sounds a bit weird to me.
A quick google search on the web finds site that all claim that an electron has a mass of about :
http://en.wikipedia.org/wiki/Electron wrote:The electron has a negative electric charge of -1.6 × 10-19 coulombs, and a mass of about 9.10 × 10-31 kg (0.51 MeV/c2), which is 1/1800 of the proton mass.
I fail to understand that if the mass (expressed in kg) of all electrons in my chair changes, that the chair doesn't change in mass expressed in kg.