Energy Changes in Chemical Reactions

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Chemical Reaction Noun

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[kem-i-kuhl ree-ak-shuhn]

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Chemical Reaction

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A process where starting substances are chemically changed into new substances by breaking and forming chemical bonds.

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Example: The image shows how methane and oxygen react to form carbon dioxide and water, illustrating a chemical reaction.

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Thermal Energy Noun

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[thur-muhl en-er-jee]

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Thermal Energy

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The total internal energy of an object due to the kinetic energy of its atoms and molecules, often perceived as heat.

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Example: Particles in a hot area move to a cooler area, showing thermal energy transfer.

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Reactants Noun

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[ree-ak-tuhnts]

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Reactants

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The initial substances that enter into and are altered during a chemical reaction to form new products.

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Example: The image shows hydrogen and oxygen as reactants forming water, illustrating reactants in a chemical reaction.

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Products Noun

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[prod-ukts]

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Products

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The new substances that are created as a result of the chemical changes that occur during a reaction.

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Example: The image shows how reactants like CH4 and O2 transform into products CO2 and H2O in a chemical reaction.

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Chemical Bonds Noun

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[kem-i-kuhl bonds]

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Chemical Bonds

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The lasting forces of attraction between atoms, ions, or molecules that enable the formation of chemical compounds.

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Example: The image shows how sodium and chlorine atoms exchange electrons to form ions, creating a stable ionic bond.

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Chemical Potential Energy Noun

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[kem-i-kuhl poh-ten-shuhl en-er-jee]

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Chemical Potential Energy

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The energy stored within the chemical bonds of a substance, which can be released during a chemical reaction.

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Example: The image shows how chemical potential energy in a battery is stored and converted to electric energy, with labeled parts for clarity.

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Endothermic Reaction Noun

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[en-doh-thur-mik ree-ak-shuhn]

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Endothermic Reaction

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A chemical reaction that absorbs more energy from its surroundings than it releases, often causing a drop in temperature.

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Example: The image shows a test tube with arrows pointing inward, indicating energy absorption in an endothermic reaction.

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Exothermic Reaction Noun

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[ek-soh-thur-mik ree-ak-shuhn]

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Exothermic Reaction

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A chemical reaction that releases more energy into its surroundings than it absorbs, often causing a rise in temperature.

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Example: The image shows a chemical reaction releasing energy as methane and oxygen form carbon dioxide and water.

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Concentration Noun

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[kon-suhn-trey-shuhn]

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Concentration

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The measure of the amount of a dissolved substance, or reactant, contained per unit of volume in a solution.

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Example: The image shows a solution with solute particles dispersed in a solvent, illustrating concentration.

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Reaction Rate Noun

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[ree-ak-shuhn reyt]

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Reaction Rate

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The speed at which reactants are converted into products over a specific period of time in a chemical reaction.

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Example: This image shows how methane and oxygen react to form carbon dioxide and water, illustrating reaction rate.