Collision Theory

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Collision Theory Noun

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[kuh-li-zhun thee-uh-ree]

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Collision Theory

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A theory stating that reactant particles must collide with sufficient energy and correct orientation for a chemical reaction to occur.

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Example: For a chemical reaction to happen, particles must collide successfully to form new substances; unsuccessful collisions do not result in a reaction.

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Activation Energy Noun

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[ak-tuh-vey-shun en-er-jee]

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Activation Energy

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The minimum amount of energy required for colliding reactant particles to initiate a chemical reaction upon impact.

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Example: This graph shows that a chemical reaction, like striking a match, needs an initial input of energy (the 'hill') to get started.

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Reaction Rate Noun

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[ree-ak-shun reyt]

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Reaction Rate

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The speed at which a chemical reaction proceeds, measured as the change in reactant or product concentration over time.

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Example: This graph shows reaction rate is the speed at which a reactant is used up. The rate is measured by the steepness (slope) of the curve.

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Catalyst Noun

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[kat-l-ist]

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Catalyst

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A substance that increases reaction rate by providing an alternative pathway with lower activation energy, without being consumed itself.

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Example: A catalytic converter uses a catalyst (special metals) to speed up the chemical reaction that changes harmful exhaust gases into safer substances.

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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 are present at the beginning of a chemical reaction and undergo a chemical change.

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Example: The substances on the left of the arrow, hydrogen (H₂) and oxygen (O₂), are the reactants that combine during a chemical reaction to form a new product.

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Products Noun

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[prod-uhkts]

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Products

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The new substances that are formed as the result of a chemical reaction between the initial reactants.

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Example: This diagram shows that in a chemical reaction, the starting substances (reactants) rearrange their atoms to form new substances, which are called the products.

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Concentration Noun

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[kon-sen-trey-shun]

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Concentration

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A measure of the amount of a substance, or the number of particles, contained within a specific volume.

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Example: This diagram compares two solutions: one with low concentration (fewer solute particles) and one with high concentration (more solute particles) in the same volume.

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Surface Area Noun

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[sur-fis air-ee-uh]

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Surface Area

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The total exposed surface of a solid substance that is available to participate in a chemical reaction.

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Example: This image shows a 3D cube and its unfolded 2D net, illustrating that surface area is the total area of all faces of an object.

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Successful Collision Noun

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[suhk-ses-fuhl kuh-li-zhun]

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Successful Collision

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A collision between reactant particles that has both sufficient energy and the correct orientation to result in a reaction.

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Example: Two particles collide with enough energy and in the right way to cause a chemical reaction, shown by the bright flash of light.

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Chemical Reaction Noun

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

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Chemical Reaction

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A process that involves the transformation of one set of chemical substances, the reactants, into another set, the products.

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Example: This image shows that in a chemical reaction, atoms in the starting molecules (reactants) rearrange to form new molecules (products).