| A | B |
|---|
| ATOM | THE SMALLEST PARTICLE IN AN ELEMENT THAT CAN ENTER INTO CHEMICAL CHANGE. |
| ATOMIC NUMBER | THE NUMBER OF PROTONS IN THE NUCLEUS OF AN ATOM. |
| ELEMENT | CANNOT BE DECOMPOSED INTO SIMPLER SUBSTANCES BY ORDINARY CHEMICAL MEANS. |
| GROUND | STATE IN WHICH ALL ELECTRONS ARE AT THEIR LOWEST POSSIBLE ENERGY LEVEL. |
| PROTON | THE POSITIVELY CHARGED PARTICLE FOUND IN THE NUCLEUS. |
| CARBONTWELVE | STANDARD FOR THE ATOMIC MASS UNIT. |
| NUCLEUS | MOST OF THE MASS IN A ATMOSPHERE IS HERE. |
| NEUTRONS | MASS # (-) ATOMIC # |
| VALENCE | ELECTRONS IN THE OUTERMOST PRINCIPAL ENERGY LEVEL. |
| NUCLEONS | PROTONS AND NEUTRONS ARE THESE. |
