Types of Chemical Reactions

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Combination Reaction Noun

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[kom-bi-nay-shun ree-ak-shun]

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Combination Reaction

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A type of chemical reaction where two or more simple substances combine to form a single, more complex product.

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Example: This diagram shows two simpler substances, hydrogen (H₂) and oxygen (O₂), combining to form a single, more complex product, water (H₂O).

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Decomposition Reaction Noun

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[dee-kom-po-zish-un ree-ak-shun]

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Decomposition Reaction

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A type of chemical reaction where a single compound breaks down into two or more simpler substances.

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Example: The large starch molecule (a polysaccharide) is broken down by digestion into many smaller, simpler glucose molecules (monosaccharides), illustrating a decomposition reaction.

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Single Replacement Reaction Noun

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[sing-gul ree-plays-ment ree-ak-shun]

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Single Replacement Reaction

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A chemical reaction where one element is substituted for another element in a compound, creating a new compound.

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Example: This diagram shows element 'A' taking the place of element 'B' in the compound 'BC', forming a new compound 'AC' and leaving 'B' by itself.

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Double Replacement Reaction Noun

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[dub-ul ree-plays-ment ree-ak-shun]

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Double Replacement Reaction

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A reaction where two compounds' positive and negative ions switch places, forming two entirely new compounds.

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Example: When two liquid solutions are mixed, their ions switch partners to form a new liquid (NaCl) and a solid precipitate (CaSO₄).

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Combustion Reaction Noun

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[kum-bus-chun ree-ak-shun]

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Combustion Reaction

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A rapid reaction between a substance and an oxidant, usually oxygen, that produces heat and light.

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Example: This diagram shows a campfire, where wood (a hydrocarbon fuel) reacts with oxygen from the air to produce carbon dioxide, water, and energy (heat and light).

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Reactant Noun

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[ree-ak-tant]

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Reactant

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A substance that participates in and undergoes change during a chemical reaction, found on the left side of an equation.

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Example: In a chemical reaction, reactants like methane and oxygen are the starting substances that combine and change to form new substances called products.

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Product Noun

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[prod-ukt]

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Product

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A substance that is formed as the result of a chemical reaction, found on the right side of an equation.

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Example: In a chemical reaction, starting materials called reactants rearrange to form new substances on the right side, which are called the products.

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Chemical Equation Noun

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[kem-i-kul ee-kway-zhun]

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Chemical Equation

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A symbolic representation of a chemical reaction using formulas to show the reactants and the resulting products.

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Example: This image shows a chemical equation where reactants (methane and oxygen) on the left rearrange their atoms to form new products (carbon dioxide and water).

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Compound Noun

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[kom-pound]

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Compound

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A 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 a carbon dioxide (CO₂) molecule, a compound formed when one carbon atom chemically bonds with two oxygen atoms.

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Hydrocarbon Noun

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[hy-dro-kar-bun]

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Hydrocarbon

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An organic compound consisting entirely of hydrogen and carbon atoms, often a reactant in combustion reactions.

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Example: This image shows a model of methane (CH₄), the simplest hydrocarbon, which is a molecule made of carbon (grey) and hydrogen (blue) atoms.