| A | B |
|---|
| periodic table | an arrangement of the elements by increasing atomic number |
| radioactive element | an element that naturally breaks down into a lighter element, giving off rays of energy and streams of particles |
| chemical property | characteristic that determines how a substance reacts with other substances |
| atomic number | number of protons in an atom of an element |
| chemical change | change that forms new substance with new properties |
| chemical bond | strong attraction between two atoms |
| physical change | change that does not effect the composition of a substance |
| neutron | uncharged particle in the nucleus of an atom |
| quark | one of two basic building blocks of an atom |
| nucleus | the cell part that controls activities of other cell parts; the central part of an atom |
| electron | negatively charged particle outside the nucleus of an atom |
| physical property | characteristic that can be observed without changing the composition of a substance |
| proton | positively charged particle in the nucleus of an atom |
| mass number | the total number of protons and neutrons in an atom |
| isotope | one of a group of atoms of an element with the same number of protons but different number of neutons |
| neutral | having no charge |
