| A | B |
|---|
| protons | positively charged particles |
| neutrons | no charge or neutral charged particles |
| electrons | negatively charged particles |
| atom | made up of protons, neutrons and electrons |
| atomic number | made up of protons |
| nucleus | made up of protons and neutrons |
| protons and electrons | always equal the same number in an element |
| element | located on the Periodic Table |
| electron shells | there are five of these that circle the nucleus |
| Shell 1 | holds 2 electrons |
| Shell 2 | holds 8 electrons |
| Shell 3 | holds 18 electrons |
| Periodic Table | the elements are arranged in order of increasing atomic mass |
