| Term | Definition |
| Atom | The smallest particle of an element,
made of electrons, protons, and neutrons. |
| Element | A pure substance composed of the
same type of atom throughout. |
| Compound | A substance made of two or more elements
that are chemically combined in fixed amounts. |
| Substance | Any form of matter that is uniform throughout
and has consistent properties. |
| Periodic Table of Elements | A table in which all the known elements are arranged
by properties and are represented by one or two letters,
referred to as chemical symbols. |
| Lithosphere | The rigid, outer part of Earth. |
| Hydrosphere | All of the water on Earth. |
| Biosphere | The sum of all living matter, made of a limited number
of elements including oxygen, carbon, hydrogen,
nitrogen, calcium, and phosphorus. |
| Atmosphere | The layer of gas surrounding planet Earth, held in
place by gravity and composed of a limited number
of elements, primarily nitrogen and oxygen. |
| Matter | Anything that has mass and takes up space. |
| Properties | Physical and chemical characteristics of matter
used to describe or identify a substance. |
| Volume | A measure of the space that matter occupies. |
| Mass | A measure of how much matter
is present in a substance. |
| Mixture | A combination of two or more substances
which do not chemically combine. |
| Uniform Composition | Made of the same evenly distributed substance or
combination of substances throughout. |
| Chemical Formula | A shorthand notation that uses chemical symbols and numbers as subscripts to represent the type and number of atoms that are present in the smallest unit of the substance |
| Oceans | The largest bodies of water on Earth, covering approximately 71% of Earth’s surface and made up of saltwater |
| Chemical Symbols | One or two letters that represent elements |
