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Chemical Reaction
Science
| Term | Definition |
|---|---|
| Chemistry | the study of the properties of matter and how matter changes. |
| element | a substance that cannot be broken down into any other substances by chemical or physical means. |
| compound | a substance made of two or more elements chemically combined in a specific ratio, or proportion. |
| mixture | made from two or more pure substances - elements, compounds, or both - that are in the same place but not combined as a new material. |
| solution | a well-mixed mixture |
| physical change | a change that alters the form or appearance of a material but does not make the material into another substance. |
| chemical change | a change in matter that produces new substances. |
| precipitate | a solid that forms from solution during a chemical reaction. |
| atom | the smallest particle of an element. |
| molecule | a combination of two or more atoms. |
| chemical bond | the force that holds atoms together. |
| chemical equation | a shorter, easier way to show chemical reactions, using symbols instead of words. |
| symbol | a one-letter or two-letter representation of an element. |
| chemical formula | a 'word' representing a compound which shows the ratio of elements in the compound. |
| subscript | shows the number of atoms of an element in a molecule. |
| reactants | the materials you have at the beginning of a chemical reaction |
| products | the different materials formed when a reaction is complete |
| conservation of matter | the principle that matter is not created or destroyed during a chemical reaction. |
| coefficient | a number in front of a chemical formula in the equation. |
| synthesis | when two or more substances (elements or compounds) combine to make a more complex substance. |
| decomposition reaction | breaks down compounds into simpler products. |
| replacement reaction | a reaction in which one element replaces another in a compound or in which two elements in different compounds trade places. |
| exothermic reaction | a reaction that releases energy in the form of heat. |
| endothermic reaction | a reaction that absorbs energy. |
| activation energy | the minimum amount of energy that has to be added to start a reaction. |
| concentration | the amount of one material in a given volume of another material. |
| catalyst | a material that increases the rate of a reaction by lowering the activation energy. |
| enzymes | provide a surface on which reactions take place. |
| combustion | a rapid reaction between oxygen and a substance called a fuel. |
| fuel | a material that releases energy when it burn. |
Created by:
lhummingbird