AP Chapter 1 Matter and Measurement Chemistry Chemistry is the study of the properties and behavior of matter. Matter is the physical material of the universe and has mass and volume, and therefore density. Matter Elements composed of a single type of atom. Molecules 2 or more atoms combined chemically to make a substance. States of Matter Gas no fixed shape or volume it takes the shape of its container and is compressible. Liquid distinct volume, but no fixed or distinct shape. It takes the shape of its container. Solid definite shape and volume. Its non-compressible. Pure Substances Pure substances can NOT be broken down by physical means. Elements cant be broken down further Compounds can ONLY be broken down by chemical means into their elements. 2H 2 O 2H 2 + O 2 (using electrolysis) Mixtures Multiple substances are involved in mixtures, each with its own properties. Mixtures are separated by physical means based on the properties of the substances in the mixture. Evaporation Filtration Sorting Mixtures Homogeneous Mixtures The same composition exists throughout the sample. Can be liquid or solid Heterogeneous Mixtures Different composition in different areas of the sample. Physical and Chemical Changes Physical Change changes the physical appearance but not the composition. State changes are physical changes. Chemical Changes changes the composition of the substance and creates a new substance with new and different properties. SI Base Units Units of Measurement Density Accuracy and Precision Accuracy How close the measured values are to the accepted values. Precision How close the measured values are to each other.