The mass of a carbon-12 atom is 12 amu. What percent of the mass is located in the nucleus? and Why is the value so close to 100%?


I can only give a simple answer, so if others have better ones, great, but here's my shot:

An electron's mass is a lot less than a proton/neutron. "When talking about relative masses, we use the term atomic mass unit (amu). Using this unit, a proton has a mass of 1.007 amu, a neutron a mass of 1.008 amu, and an electron a mass of 5.45 X 10-4 amu."

Basically, the proton and neutron is close to 1, and the electron is close to 0.

Carbon-12 means it's got a total of 12 protons and neutrons, and since carbon has 6 protons, that makes 6 neutrons. Since it's a normally charged carbon atom too, that makes 6 electrons.

Can you do the calculations yourself with that? Because now you know the masses.

Also this value should be really close to 100% because of how electrons are so much lighter than protons and neutrons; protons and neutrons are located in the nucleus and the rest of the atom is mostly empty space + some electrons, so that's why the bulk of the mass is there.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.