Term | Definition |
matter | anything that has mass and occupies space |
chemistry | the study of the composition of matter and the changes that matter undergoes |
scientific method | a logical, systematic approach to the solution of a scientific problem (making observations, testing hypotheses, developing theories) |
observation | information obtained through the senses, often involving a measurement |
hypothesis | a proposed explanation for an observation |
experiment | a repeatable procedure that is used to test a hypothesis |
independent variable | the variable that is changed during an experiment, also called a manipulated variable |
dependent variable | the variable that is observed during an experiment, also called a responding variable |
model | a representation of an object or event |
graduated cylinder | glassware used for measuring volume of a liquid |
beaker | glassware used for containing and mixing but not for measuring |
balance | instrument used for measuring mass |
significant figure | the digits that can be known precisely in a measurement plus an estimated digit |
density | a measure of how packed together the particles in a substance are; mass divided by volume |
mass | the amount of matter in an object |
volume | the amount of space occupied by an object |
physical change | a change in appearance but not in identity |
chemical change | a change that produces a new substance |
dimensional analysis | a method of problem solving that uses the units to help solve the problem |
combustion | a chemical reaction in which a fuel and oxygen react to form carbon dioxide and water |
precipitate | a solid that forms and settles out of a liquid mixture |
freezing point | the temperature at which a liquid changes to a solid |
melting point | the temperature at which a solid changes to a liquid |
signs of chemical change | formation of a gas, formation of a precipitate, change in energy, change of color or odor |
tare technique | a technique for finding the mass of an object by using the balance to zero out the mass of the container |
absolute technique | a technique for finding the mass of an object by weighing the empty container and subtracting it from the mass of the container with the object in it |
reactant | material that is present at the start of a reaction |
product | material that is formed in a chemical reaction |
solid | state of matter that has a definite volume and definite shape |
liquid | state of matter that has a definite volume and does not have a definite shape |
gas | state of matter that has no definite volume and no definite shape |
mixture | a blend of two substances that are not chemically combined |
heterogeneous mixture | a mixture that is not uniform in composition |
homogeneous mixture | a mixture that is uniform in composition |
element | the simplest form of matter; cannot be broken down further by chemical means |
compound | a substance made of two or more elements that are chemically combined |
freezing | changing from the liquid state to the solid state, requires the removal of energy |
melting | changing from the solid state to the liquid state, requires the addition of energy |
condensation | changing from the gas state to the liquid state, requires the removal of energy |
evaporation | changing from the liquid state to the gas state, requires the addition of energy |
sublimation | changing from the solid state to the gas state without going through the liquid state |
depositon | changing from the gas state to the solid state without going through the liquid state |