| A | B |
|---|
| physical changes | changes in size, shape, and state |
| chemical changes | change in which one or more new substances are formed |
| chemical reaction | when one or more substances interact to form a new substance |
| chemical equation | a "chemical sentence" that explains a chemical reaction |
| model | something used or made to represent an object, idea, or process |
| nucleus | the dense, central part of an atom |
| proton | a positively charged particle found in the nucleus of an atom |
| neutron | a particle in the nucleus of an atom that has no electric charge |
| electron | a negatively charged particle in an atom that travels around the nucleus of an atom |
| Bohr model | a model of an atom where the electrons orbit around the nucleus ("a planetary model") |
| electron cloud model | the way the electrons surround the nucleus |
| atomic number | the number of protons in an atom of that element |
| ion | an electrically charged atom |
| molecule | a particle made up of a group of atoms that are chemically bonded |
| chemical bonds | the attraction between ions that forms an ionic compound |
| radioactive elements | made up of atoms whose nuclei break down or decay |
| nuclear fission | to split the nuclei of atoms of some elements by bombarding them with neutrons |
| helpful radiation | medical research and in the treatment of certain illnesses |
| harmful radiation | gamma rays can pass through human tissue damaging cells along the way |
