Chapter 1 Matter Measurement and Problem Solving Matter something that has mass and occupies space Pure substance composed of only 1 component element vs compound o o e g carbon dioxide compound e g oxygen element Mixture composed of more than 1 component o Homogeneous inseparable by physical means e g blood o Heterogeneous separable by physical means e g chicken noodle soup Physical vs Chemical Physical property measurable without altering the composition of the substance Chemical property only measurable by altering the composition of the substance Physical change changes in state appearance no change to the comp of the substance Chemical change changes in the comp of the substance via chemical rxn e g dry ice subliming e g sugar dissolving e g burning propane gas e g rusting of iron Units of Measurement Know nano 10 9 to tera 1012 Density the mass that occupies a particular volume 1 ml 1 cm3 Significant Figures http ccnmtl columbia edu projects mmt frontiers web chapter 5 6665 html The of sigfigs in a measurement determines its certainty Exact s never limit a calculation s precision Trailing zeros no decimal shown not significant Trailing zeros decimal shown significant 1200 2 sig figs 1200 4 sig figs Consider constants conversion factors exact s Addition Subtraction of sig figs is determined by of digits past the decimal place Multiplication Division of sig figs is determined by the lowest of sig figs Combined perform 1 operation with the correct of sig figs and then the other with correct sig figs Accuracy v Precision Accuracy how close a measured value is to the actual value Precision how consistent close together a series of measured values are o o o o o o