| A | B |
|---|
| anything that has mass and takes up space | matter |
| atoms of the same element that have different numbers of neutrons | isotopes |
| the sum of an atom's protons and neutrons | mass number |
| a small particle that makes up most types of matter on Earth | atom |
| a pure substance whose smallest unit is made up of atoms of more than one element | compound |
| formed when two or more substances come together but don't combine to form a new substance | mixtures |
| elements that are usually dull in appearance and poor conductors of heat and electricity | nonmetals |
| elements that have characteristics of both metals and nonmetals | metalloids |
