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Published byLenard Anderson Modified over 9 years ago
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Units of Measurement We measure everything! see table 1.1 and 1.2
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Examples of Measurements will we use numbers that big/small in class? yep! the mole
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the mole 602,213,700,000,000,000,000,000 particles or 6.022137 x 10 23 particles scientific notation!
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Scientific Notation a way to write really big numbers
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How to go to sci. notation Numbers bigger than ten will have positive exponents that will equal how many times decimal moved to the left 36000 = 3.6 x 10 4 Numbers smaller than ten will have a negative exponents that will equal how many times it moved to the right 0.0081 = 8.1 x 10 -3
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Practice Write in scientific notation 1.914 m 2.0.000 000 000 154 g 9.14 x 10 2 m 1.54 x 10 -10 g
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How to go from sci. notation Positive exponent = decimal moves to right 8.25 X 10 4 = 82500 Negative exponent = decimal moves to left 1.2 X 10 -3 =.0012
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Practice Write in scientific notation 1.2.157 X 10 5 L 2.6.5 X 10 -2 m 215 700 L.065 m
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?’S
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which measurement is best? 1.1200g 2.1.200 x 10 3 g 3.1.2 x 10 3 g
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Significant Figures= digits recorded in measuring the more sig figs the greater the certainty
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Rules 1.All nonzeroes are significant 2.Zeroes in-between are significant 3.Zeroes to the left are not significant 4.Zeroes to the right are not significant unless they follow a decimal. 5.All numbers in scientific notation are significant 6.Exact numbers are obtained by counting or definitions such as 1 in = 2.54 cm, and are considered infinite in significance
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Practice How many sig figs are in the following? 1.0.0950 m 2.9009.0 J 3.10 km 4.60 sec = 1min 5.5.50 x 10 8 ng 3 5 1 infinite! 3
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so…which measurement is best? 1.1200g 2.1.200 x 10 3 g 3.1.2 x 10 3 g
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Adding and Subtracting Always use the least significant decimal place. example: 1253.747 + 1.1 = 1254.8 1253.757 + 1.1 = 1254.9 round up.0365578 -.00223 =.03433 or 3.433 X 10 -2
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Practice complete the following 1.8.7 g + 15.43 g + 19 g = 2.853.2 L - 627.443 L = 3.5.47 m + 11.0 m + 87.300 m = 43 g 225.8 L 103.8 m
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Multiplying and Dividing All ways go by the least number of significant figures. examples: 1253.747 X 1.1 =1379.1217 No 1400 or 1.4 x 10 3
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Practice complete the following 1.4.32 cm x 1.7 cm = 2.38.742kg ÷ 0.421 = 3.5.40 m x 3.21 m x 1.871 m = 7.3 cm 2 92.0 kg 32.4 m 3
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Combining the math Follow order of operations 55.657 -55.654 X.033 = 4.54 0.003 X.033 = 2 x 10 -5 (1 sig fig) 4.54
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Practice 8.52 + 4.1586 18.73 + 153.2 = 239.6 or 2.396 x 10 2 = 8.52 + 77.89 + 153.2 = 239.61 =
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