| A | B |
| atom | smallest particle of an element that still has the properties of the element |
| electron | particle in an atom that has a negative charge |
| element | substance that cannot be broken down into other substances |
| molecule | two or more atoms joined together by chemical bonds |
| neutron | particle in the nucleus of an atom that has no charge |
| nucleus | central core of an atom |
| proton | particle in the nucleus of an atom that has a positive charge |
| quark | particle inside protons and neutrons |
| gluon | particles that join quarks |
| electron | particle in an atom that orbits around the nucleus |
| molecule | particle that keeps the same properties no matter how small it is broken down |
| proton | the number of these determine what element something is |
| matter | something that takes up space and has mass |
| solid | more molecules than any other state of matter |
| solid, liquid, gas | the three states of matter |
| gas | fewer molecules than any other state of matter |
| atom | molecules contain two or more of these joined together |
| atom | the building block of matter |