| A | B |
| Atom | The smallest form of a pure substance of matter. |
| Neutron | Subatomic (part of the atom) particle with a neutral charge (no charge) found in the nucleus (0) |
| Proton | Subatomic (part of the atom) particle with a positive charge found in the nucleus (+) |
| Electron | Subatomic (part of the atom) particle with a negative charge found in the electron cloud (-) |
| Molecule | 2 or more atoms chemically bonded. |
| Element | 1. The most basic form of a pure substance. 2. Can be identified by it's atomic number 3. Each have their own unique specific properties |
| Compound | A type of molecule made of atoms from at least two different elements |
| Atomic number | The number of protons found in the nucleus of an atom |
| Mass number | The SUM of the protons and neutrons in the nucleus |
| Periodic | Following a repeating pattern |
| Periods | Rows of elements on the periodic table (they go across) |
| Groups | Columns of elements on the periodic table (they go vertically, up and down) |
| Electron cloud | This is where electrons are found orbiting the nucleus. The energy levels (invisible paths) that electrons orbit on are found here. |
| Nucleus | Positively charged dense center of the atom. This contains protons and neutrons. |
| Energy levels | The invisible paths electrons orbit the nucleus on. |