| A | B |
|---|
| atom | smallest unit of matter |
| proton | positve subatomic particle |
| neutron | neutral subatomic particle |
| electron | negative subatomic particle |
| isotopes | atoms of the same element that vary in mass number |
| atomic number | number of protons in an atom |
| mass number | sum of protons and neutrons |
| nucleus | location of protons and neutrons |
| Described the solid sphere model of the atom | John Dalton |
| Discovered the electron | J.J. Thomson |
| Energy level | Location of the electron |
| Nucleon | Subatomic particles found in the nucleus |
| Described the atom as mostly empty space with a small positive nucleus | Rutherford |
| Average atomic mass | Weighted average of the relative atomic masses of all naturally occurring isotopes of an element |
| Carbon | Nuclide upon which relative atomic masses are based |
| Protium | Isotope of hydrogen with zero neutrons |
| Deuterium | Isotope of hydrogen with one neutron |
| Trtium | Isotope of hydrogen with two neutrons |
| Ion | Charged particle |
| Cation | Charged particle formed when an atom has lost 1 or more electrons |
| Anion | Charged particle formed when an atom has gained 1 or more electrons |
