Term | Definition |
subscript | A number written below and to the right of a chemical symbol that shows the number of atoms. |
chemical formula | A shorthand notation that uses chemical symbols and subscripts to represent the type and number of atoms in the smallest unit of the substance. |
chemical reaction | The process by which one or more substances change to produce one or more different substances. |
chemical equation | Chemical formulas and symbols written to represent an entire reaction. |
coefficient | A number placed in front of a chemical symbol or formula in order to balance the equation. |
balanced chemical equation | A symbolic representation of a chemical reaction in which both sides of the equation contain equivalent numbers of atoms of each element. The mass and the charge must be balanced on both sides of the reaction. |
reactants | Substances that take part in and are changed by a chemical reaction |
products | substances produced during a chemical reaction |
Law of Conservation of Matter | The mass of all reactants must equal the mass of all products. Matter is neither created nor destroyed. |
physical change | affects size, shape, state of matter, or color of a substance, but does not turn it into a new substance |
chemical change | one or more substances are changed into entirely new substances because their atoms are rearranged |
element | a pure substance made entirely of one type of atom |
atom | the smallest unit of an element |
molecule | 2 or more atoms bonded together by valence electrons |
compound | a pure substance made of 2 or more types of atoms bonded together by valence electrons |
exothermic | describes a chemical reaction that produces heat energy |
endothermic | describes a chemical reaction that absorbs heat energy |
carbon | the one element that is found in all organic compounds |
valence electrons | the electrons that are in the outermost energy level of an atom |
evidence | indication that an event has occurred |
substance | an element or compound that can only be separated or combined to make new substances by means of a chemical reaction |
precipitate | a solid that is deposited in a solution |