Mixtures and Solutions

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Atom Noun

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[at-uhm]

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Atom

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The smallest functional unit of all matter, consisting of a nucleus of protons and neutrons and orbiting electrons.

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

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Chemical Bond Noun

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[kem-i-kuhl bond]

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Chemical Bond

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The force of attraction that holds atoms together in a molecule or compound, resulting from electron interactions.

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Example: This image shows how atoms, like Oxygen (O) and Hydrogen (H), are held together by chemical bonds to form a single water molecule.

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Covalent Bond Noun

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[koh-vey-luhnt bond]

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Covalent Bond

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A type of chemical bond formed when two atoms achieve stability by sharing one or more pairs of electrons.

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Example: This diagram shows two hydrogen atoms and one oxygen atom sharing their outer electrons to form strong connections, called covalent bonds, creating a water molecule.

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Molecule Noun

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[mol-i-kyool]

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Molecule

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A neutral group of two or more atoms held together by strong chemical bonds, specifically covalent bonds.

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

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Element Noun

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[el-uh-muhnt]

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Element

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A pure substance consisting of only one type of atom, which cannot be broken down into simpler substances.

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Example: This diagram shows the structure of a single atom, which is the basic unit that makes up an element. All atoms of a specific element are the same.

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Diatomic Element Noun

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[dahy-uh-tom-ik el-uh-muhnt]

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Diatomic Element

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An element that naturally exists as a stable molecule containing two atoms bonded together, rather than as individual atoms.

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Example: This image shows a molecule of oxygen (O₂), which is a diatomic element because it consists of two atoms of the same element chemically bonded together.

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Compound Noun

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[kom-pound]

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Compound

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A pure substance formed when two or more different chemical elements are chemically bonded together in a fixed ratio.

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Example: This diagram shows that the compound water (H₂O) is made of two hydrogen (H) atoms chemically bonded to one oxygen (O) atom.

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Fixed Composition Noun

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[fikst kom-puh-zish-uhn]

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Fixed Composition

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The principle that a given chemical compound always contains its component elements in a fixed ratio by mass.

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Example: This diagram shows that water (H₂O) is always formed from hydrogen and oxygen in a fixed 1:8 ratio by mass, demonstrating the principle of fixed composition for a chemical compound.

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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 form of matter with a constant chemical composition and characteristic properties, consisting of one element or compound.

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Example: Gold is a pure substance because it is an element made up of only one type of atom, which cannot be broken down by physical means.

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Mixture Noun

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[miks-cher]

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Mixture

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A material made up of two or more different substances which are physically combined but not chemically bonded together.

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Example: This image shows that a mixture is formed when two or more substances, like salt and water, are physically combined without a chemical reaction.