Scientific Notation and Significant Figures Chemistry and Society Fall 2006 Giddy-up!

Scientific Notation A system of shorthand –Helps make big number smaller –6.023 x –or 602,300,000,000,000,000,000,000 /scienceopticsu/powersof10/

Practice Convert the following to expanded forms: 1) ) ) ) )2.3 x )0.41 x 10 -6

Convert the following to scientific notation: 1) ) ) ) )4.5 x ) x ) 7.0 x ) 1.23 x 10 -2

V. USING A SCIENTIFIC CALCULATOR “E” does NOT mean error – it means exponential

Significant Digits Significant Digits- are important because you can not imply more accuracy than you measured –Lehner’s rules of Significant digits: All digits are significant EXCEPT –Zeros holding places to the left of non-zero number » = 3 significant digits

Zeros to the right of non-zero numbers that were NOT measured 300 meters = 1 significant digit 300. Meters = 3 significant digits Significant Digits

g g g round off to two decimal places g Significant Figures in the result of Addition or Subtraction  The result must be expressed with the same absolute uncertainty found in the least precisely determined quantity used to obtain the result.  Uses the Decimal places

 The result of these operations will contain the same number of significant figures as the quantity in the calculation containing the fewest number of significant figures. Significant Figures in the result of Multiplication and Division Density = 39.27g 20. mL 4 significant figures 1 significant figure = g/mL = 2 g/mL