| A | B |
|---|
| atom | smallest piece of matter |
| nucleus | positively charged center of an atom |
| proton | particles with an electric charge of +1 have a charge |
| neutron | particle with no electrical charge |
| electron | particles with an electrical charge of +1 |
| quark | the smaller particles that make up protons and neutrons |
| electron cloud | an area around the nucleus of that atom where its electrons are found |
| atomic number | number of proton's in an atom's nucleus |
| mass number | the sum of the number of protons and neutrons in the nucleus of an atom |
| isotope | atoms of the same element that have different numbers of neutrons |
| average atomic mass | the weighted-average mass of the mixture of its isotopes |
