Chemical Changes Review

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What is an element?

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An element is a pure substance that cannot be broken down into simpler substances by chemical means. Examples include gold (Au), oxygen (O), and silver (Ag).

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What is a compound?

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A compound is a substance formed when two or more elements are chemically bonded together. An example is water (H2O), which is made of hydrogen and oxygen.

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What is a chemical change?

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A chemical change is a process where one or more substances are transformed into different substances with new properties. Examples include rusting iron and burning wood.

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What are some indicators of a chemical change?

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Indicators of a chemical change include a change in color, the formation of a gas (bubbling or fizzing), the formation of a precipitate (solid), and a change in temperature.

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What is a physical change?

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

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What happens during a chemical reaction?

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During a chemical reaction, reactants are transformed into products, which have different properties than the reactants.

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

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A physical change does not change the chemical composition of a substance, while a chemical change results in the formation of new substances.

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What is a precipitate?

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A precipitate is a solid that forms and settles out of a liquid mixture during a chemical reaction.

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What does it mean when a substance dissolves?

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When a substance dissolves, it breaks down into smaller particles and mixes uniformly with a solvent, but this is a physical change, not a chemical change.

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What is the significance of color change in a chemical reaction?

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A color change can indicate that a chemical reaction has occurred, as it often signifies the formation of new substances.