| A | B |
|---|
| Smallest pieece of matter that cannot be broken down. | Atom |
| A simple pure substance that cannot be changed into a simpler substance. | Element |
| Early atomic model which proposed that electrons orbit in fixed orbits around the nucleus. | Bohr Model |
| Atomic Model that represents the region where electrons would probably be found swirling around the atom. | Electron Cloud Model |
| Two or more atoms with specific properties that bond together. | Molecule |
| Pure substance made of more than one element. | Compound |
| One or two letters used to represent an element. | Symbol |
| Smaller particles that make up an atom including protons, neutrons and electrons. | Subatomic Particles |
| Center of the atom where 99.9% of the atoms mass is located. | Nucleus |
| Positively charged particle. | Proton |
| A neutrally charged particle found in nucleus of an atom. | Neutron |
| Negatively charged particles which orbit the nucleus. | Electrons |
| the number of protons in an element. | Atomic Number |
| The sum mass(or weight) of the protons and neutrons in an atom. | Atomic Mass |
| Atoms of the same element with a different number of neutrons. | Isotopes |
| The unit of measure of the mass of an atom. | Atomic Mass Unit |
