Matter Glossary

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Matter

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Definition: Anything that has mass and occupies space. Example: Air, water, rocks, and humans are all examples of matter.

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Atom

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Definition: The basic unit of a chemical element, made up of protons, neutrons, and electrons. Example: Hydrogen (H) and oxygen (O) atoms combine to form water (H₂O).

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Molecule

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Definition: A group of two or more atoms bonded together. Example: A water molecule (H₂O) is made of two hydrogen atoms and one oxygen atom.

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Physical Change

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Definition: A change in the form or appearance of matter without changing its chemical composition. Example: Ice melting into water or tearing a piece of paper.

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Chemical Change

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Definition: A process where one or more substances are transformed into different substances with new chemical properties. Example: Burning wood, where it turns into ash, carbon dioxide, and water vapor.

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Physical Property

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Definition: A characteristic of matter that can be observed or measured without changing its composition. Example: Color, density, mass, volume, and state (solid, liquid, gas).

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Chemical Property

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Definition: A characteristic of matter that becomes evident during a chemical reaction; it describes the substance’s ability to change into different substances. Example: Flammability, acidity, reactivity with water.

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Solid

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Definition: A state of matter with a definite shape and volume. Example: Ice, a rock, or a block of wood.

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Liquid

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Definition: A state of matter that has a definite volume but takes the shape of its container. Example: Water, oil, and juice.

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Gas

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Definition: A state of matter that does not have a definite shape or volume and can expand to fill its container. Example: Oxygen, carbon dioxide, and steam.