| A | B |
|---|
| Matter | Anything that has mass and takes up space. |
| Mass | The measure of the amount of matter in an object. |
| Atom | The smallest particle of an element that can exist and keep the element's chemica properties. |
| Electron | A particle with a negative charge that is found in orbit around the nucleus. |
| Neutron | A particle with no charge that is found in the nucleus of an atom. |
| Proton | A particle with a positive charge that is found in the nucleus of an atom. |
| Nucleus | The dense center of an atom. It contains protons and neutrons. |
| Orbits or Shells | Paths that electrons move in around the nucleus. |
| Periodic table | A chart that lists all elements arranged in order from the lowest atomic number to highest atomic number. It contains facts about the elements. |
| Element | A substance that cannot be changed into a simpler substance. It is made of only one kind of atom. |
| Ion | A charged particle formed when an atom gains or loses electrons. |
| Atomic weight | The total number of particles in the nucleus. |
| Atomic number | The number of protons found in the nucleus. |
| Isotope | An atom of the same element with a different number of neutrons. |
