Hydrogen has 1 and Carbon has 6. The atomic number is the same as the number of protrons. The atomic weight is the number of neutrons plus the number of protons in the nucleus of atoms. Atomic mas and atomic weight are the same. It would change for isotopes.
Electrons are very light.
Only about 30 grams or 1 ounce of the human body is electrons. Isotopes are elements which may differ in the number of neutrons in the nucleus. Thalium is used to detect blocked blood vessels in the heart. There are no side effects with isotopes. C. Atomic Structure 1.