the number of protons, electrons and neutrons
Explanation:
- The atomic number of an element gives the number of protons in its nucleus.
- For a neutral atom, the number of electrons is equal to the number of protons.
- The atomic weight, or atomic mass, is approximately equal to the sum of the number of protons and neutrons in the nucleus. By rounding the atomic weight to the nearest whole number, you can obtain the mass number. Subtracting the atomic number (number of protons) from the mass number gives you the number of neutrons.