1. Sig Figs

2. Scientific Notation In science, we often come across either very large or very small numbers, so we use Scientific Notation as a way to simplify them. Some numbers hard to work with: Mass of one atom = 0.000000000000000000000000000000091 kg # atoms in 2 grams of hydrogen = 1200000000000000000000000 atoms

3. Scientific Notation Easier: Mass of one electron = 9.1 x 10 -32 # atoms in 2 g hydrogen = 1.2 x 10 24

4. In Scientific Notation, a number is written as the product of two numbers: A coefficient, and 10 raised to a power (exponent). The coefficient is always greater than or equal to 1, and less than 10 M x 10 n M = Coefficient between 1 and 10 10 is the base n is the exponent

5. Scientific Notation Worksheet Numbers > 1 have a positive exponent 5.2 x 10 3 Numbers < 1 have a negative exponent 9.65 x 10 -4

6. The Importance of Measurement Ex: 2011. converted to scientific notation: In this case: In order for the coefficient to be between 1 and 10, the decimal has to move 3 places to the left. The decimal moved 3 times, so the value of the exponent is 3 The number (2011) is bigger than 1, so the exponent will be positive. (10 3 = 1000., so this reads 2.011 x 1000 which = 2011.) Ex: 0.036 converted to scientific notation: In this case: In order for the coefficient to be between 1 and 10, the decimal has to move 2 places to the right. The decimal moved 2 times, so the value of the exponent is 2 The number (0.036) is less than 1, so the exponent will be negative. (10 -2 = 0.01, so this reads 3.6 x 0.01 which = 0.036) 2.011x 10 3 + 3.6 x 10 -2

7. The Importance of Measurement 1.420 x 10 -9 2 x 10 6 Convert the following numbers from standard to scientific notation 2 000 000.0.000 000 001 420 Convert the following numbers from scientific to standard notation 7.29 x 10 15 7 290 000 000 000 000. 9.25 x 10 -11 0.000 000 000 092 5 Practice

23. Significant Figures We keep track of measurement accuracy through significant digits(Sig Digs) also called significant figures (Sig. Fig) A measurement is considered to be more accurate if it has more significant digits Significant Figures = all known digits plus one estimated digit

24. Significant Figures RULES 1) No zeros? All significant. 377 2) All sandwich zeros significant. 307 3) Leading zeros are not significant. 0.00312 4) If digits are left of a decimal then zeros right of a decimal are significant3.00 5) Scientific notation indicates significant figures when numbers end in zero 300 = 3 x 10 2 or 3.00 x 10 2 When you have to guess, zeros don’t count

25. Uncertainty in Measurements Practice: Count the number of significant digits in each measurement. 0.05730 meters8.750 x 10 -2 centimeters 8765 seconds 200. yards 0.00073 milliliters200 yards200.0 yards 40.070 grams101010 milliseconds 44 4 4 55 3 21

26. Uncertainty in Measurements Accuracy is a measure of how close the measurement is to the actual, or “true value” of what was measured. Actual blood glucose level = 94.899 mg/dL

27. Uncertainty in Measurements Precision is a measure of how close your measurements are to each other. -measurements do not have to be accurate to be precise -measurements can be both precise and accurate, or neither.