| A | B |
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| gas | the state of matter in which the molecules of a substance are very loosely bound to one another and can expand freely in a con-confined space. Gases do not have any fixed shape or volume; they are also lighter and thinner than solids and liquids. |
| liquid | the state of matter in which the molecules of a substance are loosely bound to one another. Liquids have the bility to flow and take the shape of their own containers. |
| mass | A measure of the amount of matter ina n object. |
| matter | anything that has mass and takes up space. All living and non-living things are made up of matter. Matter can take the form of a solid, liquid, or gas. |
| physicall properties | characteristics of a subsance that can be observed without a chemical reaction and can be identified with our five senses. |
| solid | the state of matter in which the molecules of a substance are tightly bound to one another. Solids have shape and rigidity. |
| density | the weight (usually in grams) of a substance for each unit of volume (usually in millimeters). |
| atoms | the smallest particles of elements. Atoms are so small they can be observed only through a microscope. Atoms are composed of protons, neutrons, and elctrons. |
| Chemical property | characteristics of a substance that can be observed only when one substance changes into another in a reaction. |
| compounds | substances made of two or more elements that have combined in such a way that each of them loses its own special; physical and chemical properties. |
| electrons | negative electrically charged particles found in an atom. |
| element | matter made up of one kind of atom. There are 107 elements that scientists know of. |
| mixture | A substance that is made up of two or more elements or compounds that have not been chemically combined. Each element or compound has not lost its own physical or chemical properties. |
| molecules | The smallest unit of a chemical compound. Molecules are made up of smaller particles called atoms. In most cases, one molecule is made up of several atoms. |
| neutrons | particles found in the mucleus of an atom that have no charge. |
| nucleus | the center part of an atom made up of smaller particles-protons |
| proton | positively charged particles found in the nucleus. |
