...using the gold foil to demonstrate the nucleus to show their deflection as it would with a nucleus
A ion is an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.
An isotope is each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.
Mass number is the number of protons and neutrons in an atom, and it tells us about the mass of the atom in amu, or atomic mass units. Atomic mass is the average mass of all the isotopes of a certain type. It is a weighted average that takes into account the abundances of all of the different isotopes
atomic mass and percent...
...abundance of each naturally occurring isotope