| A | B |
|---|
| matter | anything that has mass and takes up space |
| atom | a small particle that makes up most types of matter |
| law of conservation of matter | matter cannot be created or destroyed-it only changes form |
| electrons | negatively charged particles |
| nucleus | positively charged, central part of the atom |
| protons | positively charged particles in the nucleus |
| neutrons | uncharged particles |
| element | matter made up of only one hind of atom |
| isotopes | atoms of the same element that have different numbers of neutrons |
| mass number | total number of protons and neutrons inside the nucleus of an atom |
| atomic number | total number of protons in the nucleus of an atom |
| compound | a substance whose smallest unit is made up of atoms of more than one element bonded together |
| chemical formula | combination of letters and numbers that represent what elements that make up a substance |
| 115 | at least this many elements are known |
