Chemical and Physical Changes

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What is a chemical change?

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A process where substances combine or break apart to form new substances, often accompanied by energy changes, color changes, gas production, or precipitate formation.

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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, such as changes in state (solid, liquid, gas), shape, or size.

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What is a reactant in a chemical equation?

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The starting substances that undergo a chemical change, found on the left side of a chemical equation.

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What is a product in a chemical equation?

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The substances formed as a result of a chemical reaction, found on the right side of a chemical equation.

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What does the coefficient in a chemical equation represent?

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The number placed before a chemical formula that indicates how many molecules or moles of that substance are involved in the reaction.

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What does the subscript in a chemical formula indicate?

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The number written below and to the right of a chemical symbol that shows how many atoms of that element are present in a molecule.

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What is an example of a physical change?

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Evaporating water.

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What is an example of a chemical change?

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Fizzing, foaming, and burning.

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What is the law of conservation of mass?

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In a chemical reaction, mass is neither created nor destroyed; the total mass of reactants equals the total mass of products.

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What is an endothermic reaction?

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A chemical reaction that absorbs heat from its surroundings, resulting in a temperature decrease in the environment.