| A | B |
|---|
| Atom | Smallest particle of an element having characteristics of that element |
| Element | Substance in which all atoms in a sample are alike |
| Nucleus | Positively charged center of an atom |
| Proton | Nuclear particle with a positive charge |
| Electron | Negatively charged particles that move around nucleus |
| Neutron | Nuclear particle with no charge |
| Symbol | Abbreviation used to represent an element |
| Isotope | Atoms of same element having different numbers of neutrons |
| Mass Number | Sum of the number of protons and neutrons in an atom's nucleus |
| Atomic Number | Number of protons in an atom's nucleus |
| Subatomic Particle | Particles which are smaller than an atom |
| Energy Level | Place where an electron is likely to be found |
| Bohr Model | Model showing location, number of protons, neutrons and electrons |
| Periodic Table | Table of elements arranged by patterns in properties |
| Atomic Mass Unit | Mass of a proton or neutron |
| Electron Cloud Model | Model describing where electrons are most likely to be found |
