Properties and Atoms

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Substance Noun

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[suhb-stuhns]

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Substance

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Matter that has a specific and uniform composition and a unique set of properties that can be used for identification.

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Example: These gold bars represent a pure substance because they are made of only one type of element, gold (Au), with a uniform composition.

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Property Noun

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[prop-er-tee]

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Property

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A characteristic of a substance that can be observed or measured and is consistently used for its identification.

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Example: This image shows different minerals, each with unique properties like color (green, blue, yellow) and texture, which are characteristics used to identify them.

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Pure Substance Noun

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[pyoor suhb-stuhns]

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Pure Substance

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A substance consisting of only one type of atom or one type of molecule, possessing distinct and characteristic properties.

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Example: This image shows multiple identical water molecules (H₂O), which is an example of a pure substance called a compound.

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Physical Properties Noun

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[fiz-i-kuhl prop-er-teez]

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Physical Properties

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Characteristics of a substance that can be observed or measured without changing the substance's fundamental chemical identity or composition.

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Example: This image shows that physical properties, like a diamond's hardness or an ice cube's melting point, can be observed without changing the substance.

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Chemical Properties Noun

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[kem-i-kuhl prop-er-teez]

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Chemical Properties

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Characteristics describing a substance's ability to undergo a chemical change or reaction to form entirely new substances.

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Example: This image shows how a chemical property works by showing a chemical reaction, where original substances (reactants) rearrange their atoms to form new substances (products).

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Atom Noun

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[at-uhm]

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Atom

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The smallest and most fundamental unit of a chemical element that constitutes all matter in the universe.

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Example: This diagram shows the parts of an atom: a central nucleus with protons and neutrons, and electrons orbiting the nucleus in shells.

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Scale Noun

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[skeyl]

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Scale

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The relative size or magnitude of something, used to relate macroscopic observations to the unobservable atomic level.

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Example: This balance scale shows that the rock has more mass than the feather, causing its side of the scale to go down.

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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 chemically bonded together, forming the smallest fundamental unit of a chemical compound.

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Example: This image shows how two hydrogen (H) atoms and one oxygen (O) atom bond together to form a single water molecule (H₂O).

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Extended Structure Noun

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[ik-sten-did struhk-cher]

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Extended Structure

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A large, repeating three-dimensional arrangement of atoms or ions, typically found in solid materials like crystals.

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Example: This image shows how sodium (Na+) and chloride (Cl-) ions bond together in a large, repeating 3D grid to form a salt crystal.

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Scientific Model Noun

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[sahy-uhn-tif-ik mod-l]

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Scientific Model

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A representation used to study phenomena that are too large, small, or complex to observe and analyze directly.

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Example: This diagram is a simplified model of a sodium atom, showing its nucleus and electrons, which helps scientists understand atomic structure.