2024 Atoms and Matter Retake/Make-up

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What is an element?

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A pure substance that cannot be broken down into simpler substances by chemical means. Examples include hydrogen (H), oxygen (O), and gold (Au).

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What is a compound?

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A substance formed when two or more elements are chemically bonded together. Examples include water (H2O) and carbon dioxide (CO2).

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What is a mixture?

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A combination of two or more substances that are not chemically bonded. Examples include air (a mixture of gases) and salad (a mixture of vegetables).

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What are isotopes?

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Atoms of the same element that have the same number of protons but different numbers of neutrons. Example: Carbon-12 and Carbon-14 are isotopes of carbon.

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What is a mass number?

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The total number of protons and neutrons in an atom's nucleus. For example, the mass number of an atom with 3 protons and 4 neutrons is 7.

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What is a chemical change?

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A change that results in the formation of new chemical substances. Indicators include color change, gas production, and odor change.

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What is a physical change?

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A change that affects one or more physical properties of a substance without altering its chemical composition. Examples include melting ice and boiling water.

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What is the difference between a chemical change and a physical change?

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A chemical change results in new substances being formed, while a physical change does not change the substance's chemical identity.

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What is an ion?

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An atom or molecule that has gained or lost one or more electrons, resulting in a net electrical charge. Example: Na+ (sodium ion) and Cl- (chloride ion).

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What is a chemical reaction?

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A process in which reactants are transformed into products through the breaking and forming of chemical bonds.