Element, Compound, Mixture

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Matter Noun

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[mat-er]

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Matter

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Anything that has mass and occupies space, serving as the substance of which all physical objects are composed.

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Example: This image shows the three states of matter—solid, liquid, and gas—by comparing their macroscopic appearance (ice, water, cloud) and microscopic particle arrangement.

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Atom Noun

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[at-uhm]

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Atom

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The fundamental building block of all matter, consisting of a nucleus and electrons, of which elements are composed.

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Example: This diagram shows an atom's basic structure, with a central nucleus containing protons and neutrons, and electrons orbiting the nucleus in shells.

Front

Pure Substance Noun

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[pyoor suhb-stuhns]

Back

Pure Substance

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Matter that has a uniform chemical composition and distinct properties, consisting of only one type of element or compound.

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Example: This image shows bars of pure gold. Gold is an element, and since it is made of only one type of atom, it is a pure substance.

Front

Element Noun

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[el-uh-muhnt]

Back

Element

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A pure substance composed of only one type of atom that cannot be broken down into simpler substances by chemical means.

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Example: This diagram shows a single atom of Oxygen, which is an element. All elements are made of only one type of atom.

Front

Compound Noun

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[kom-pound]

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Compound

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A substance formed from two or more different elements chemically bonded together in a fixed, definite proportion by mass.

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Example: This diagram shows a molecule of carbon dioxide (CO₂), a compound where one carbon atom is chemically bonded to two oxygen atoms.

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Molecule Noun

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[mol-i-kyool]

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Molecule

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A group of two or more atoms, of the same or different elements, held together by chemical bonds.

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Example: This image shows a single molecule of water, formed when two hydrogen (H) atoms chemically bond with one oxygen (O) atom.

Front

Chemical Formula Noun

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[kem-i-kuhl fawr-myuh-luh]

Back

Chemical Formula

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A representation using chemical symbols and subscripts to show the number of atoms of each element in a molecule.

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Example: The chemical formula CH₄ shows that a methane molecule is a compound made of one carbon (C) atom and four hydrogen (H) atoms.

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Mixture Noun

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[miks-cher]

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Mixture

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A physical combination of two or more substances that are not chemically bonded and retain their own individual properties.

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Example: This diagram shows that a mixture is formed when two substances, like salt and water, are physically combined without a chemical reaction, resulting in a solution.

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Homogeneous Mixture Noun

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[hoh-muh-jee-nee-uhs miks-cher]

Back

Homogeneous Mixture

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A mixture in which the components are evenly distributed and have a uniform composition that cannot be visually distinguished.

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Example: This diagram shows a solution, a type of homogeneous mixture. The solute particles are evenly mixed with the solvent particles, so the mixture appears uniform.

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Heterogeneous Mixture Noun

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[het-er-uh-jee-nee-uhs miks-cher]

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Heterogeneous Mixture

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A mixture in which the components are not evenly distributed and can be easily distinguished by sight.

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Example: When oil and water are shaken, they form a heterogeneous mixture because the oil droplets do not dissolve and remain visibly separate from the water.