number of indicates how atoms in a many atoms or molecule or the molecules of each ratio of reactant and elements in a product compound 11. 12. product reactants a substance formed a substance that as a result of a enters into a chemical reaction chemical reaction 13. 14. endothermic exothermic reaction reaction a chemical a chemical reaction reaction that that releases absorbs energy energy as heat or which makes it light feel colder 15. 16. synthesis decomposition a chemical a chemical reaction reaction in that breaks down a which two or compound into more simple simpler products substances combine to form a new, more complex substance 17. 18. precipitate replacement a solid that forms during a chemical a reaction in reaction which one element replaces another in a compound, or in which two elements in different compounds trade places
number of atoms in a molecule or the ratio of elements in a compound indicates how many atoms or molecules of each reactant and product 11. reactants a substance that enters into a chemical reaction 12. product a substance formed as a result of a chemical reaction 13. endothermic reaction a chemical reaction that absorbs energy which makes it feel colder 14. exothermic reaction a chemical reaction that releases energy as heat or light 15. synthesis a chemical reaction in which two or more simple substances combine to form a new, more complex substance 16. decomposition a chemical reaction that breaks down a compound into simpler products 17. replacement a reaction in which one element replaces another in a compound, or in which two elements in different compounds trade places 18. precipitate a solid that forms during a chemical reaction