- Recall the approximate radius of an atom (0.1 nm) and its nucleus.
- Recall the relative masses of protons (1), neutrons (1), and electrons (very small).
- Define mass number as the sum of protons and neutrons.
- Define isotopes as atoms of the same element with different numbers of neutrons.
- Calculate the number of protons, neutrons, and electrons in an atom or ion given atomic and mass numbers.
