CHEM 121A Lecture Notes - Lecture 2: Scientific Notation, Decimal Mark, International System Of Units
Document Summary
Prefixes indicate the decimal fraction or multiplets of various units. Prefixes are constant regardless of the unit (gram vs. meter) How many 0"s and where the decimal point goes. Temperature: measurement of how hot or cold an object is. Physical property that determines direction of heat flow. Each degree is 1/100th the temperature between m. p. to b. p. Absolute zero: 0 k = -273. 15 celsius (lowest attainable temperature) Ach degree is 1/180th the temperature between m. p. Supposed developed by physicist/astronomer with freezing point set at 32 degree fahrenheit. Units to measure things outside the base si units. Used as conversion factors (ratios) for dimensional analysis. Ie: 1 kg iron = 1 kg air. Exact number: value that is known exactly. Accuracy: how closely our individual measurements agree with the correct or (cid:548)true(cid:549) value (bullseye) Precision: how closely individual measurements are with one another (cluster and consistency) 2. 24 grams vs. 2. 2405 grams (3 significant figures vs 5 significant figures)
