Which particle has a very small mass compared with protons and neutrons?

Which particle has a very small mass compared with protons and neutrons?

• A. Proton
• B. Electron
• C. Neutron
• D. Positron

Answer: (B)

Inside atoms, most of the mass comes from the nucleus—protons and neutrons—while electrons are far lighter. Protons and neutrons each have about 1 atomic mass unit, whereas an electron weighs only about 1/1836 of that. So the electron is the very light particle compared with protons and neutrons, which is why it’s described as having a very small mass in this context. The positron has the same tiny mass as the electron, but in basic chemistry contexts we focus on electrons as the light, familiar particle within atoms.

Inside atoms, most of the mass comes from the nucleus—protons and neutrons—while electrons are far lighter. Protons and neutrons each have about 1 atomic mass unit, whereas an electron weighs only about 1/1836 of that. So the electron is the very light particle compared with protons and neutrons, which is why it’s described as having a very small mass in this context. The positron has the same tiny mass as the electron, but in basic chemistry contexts we focus on electrons as the light, familiar particle within atoms.