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Science Flash Cards

Science Definitions

Element Substance that cannot be broken down into any other substances by chemical or physical means.
Compound A substance made of two or more element chemically combined in a specific ratio, or proportion.
Mixture Is made up of 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 material into another substance.
Chemical Change A change in matter that produces new substances. Example: substances --> made + steps.
Precipitate A solid that forms from solution during a chemical reaction.
Atom The smallest particle of an element/
Molecule The 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 Most elements are represented by a one word letter or two letter symbol.
Chemical Formula A compound is represented by a "word" called a chemical reactions, using symbols instead of words.
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 When the reaction is complete, you have different materials, called the products of the 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 in 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 Provides a surface on which reactions takes place.
Combustion A rapid reaction between oxygen and a substance called a fuel.
Fuel A material that releases energy when it burns.
Created by: Laddi_4