1. Measurement

2. I.Measurement A.A quantity that has both a number and a unit 1.Which is a measurement? i.12 cm ii.134.54 iii.0.0034

3. II.The Metric System A.Standard units of measurement (SI) B.Temperature conversion: QuantityUnitSymbol Lengthmeterm Masskilogramkg TemperatureKelvinK Timeseconds Amount of substance molemol °C + 273 = Kelvin

4. III.Metric Prefixes PrefixMeaningFactor Kilo (k) 1000 times larger than the unit 10 3 Centi (c) 100 times smaller than the unit 10 − 2 Milli (m) 1000 times smaller than the unit 10 − 3 Micro ( μ) 1 million times smaller than the unit 10 − 6 Nano (n) 1 billion times smaller than the unit 10 − 9

5. IV.Scientific Notation A.Used to write really big and small numbers 6.02 ×10 23 B.The coefficient is equal to or greater than 1 and less than 10 C.The exponent is a positive or negative integer

6. A.For large numbers— 1.move the decimal to the left until one digit remains in front 2.Count the number of times the decimal moves 3.The exponent is positive 4.Example: i.3,000  3 ×10 3 ii.405,000  4.05 ×10 5 V.Writing Scientific Notation

7. B.For small numbers— 1.move the decimal to the right until one digit is in front 2.Count the number of times the decimal moves 3.The exponent is negative 4.Example: i.0.00034  3.4 ×10 −4 ii.0.0000005070  4.05 ×10 −6

8. A.How close a measurement comes to the actual value of whatever is measured B.The more # of significant digits, the more accurate the value VI.Accuracy

9. A.How close a series of measurements are to one another or “repeatability” B.You must compare two or more measurements to each other VII. Precision

10. VIII. Accuracy vs Precision

11. A.Example: Jack has a height of 70 inches. Which sets of measurements are 1.Accurate and precise 2.Precise but not accurate 3.Neither precise nor accurate i.69.5 in., 70.5 in., 70.1 in. ii.45.3 in., 62.1 in., 84.3 in iii.78.3 in., 78.0 in., 78.1 in

12. A.To find out how close you are to an accepted or actual value B.Percent error =  exp val – act val  x 100% act val IX. Percent Error error

13. C.Example: Your data reads 99.1g but the accepted value is 101.0g, what is your percent error? Percent error = 99.1g − 101.0g × 100 101.0g %error = 1.88%

14.  Includes all the digits that are known, plus one that is estimated X.Measuring with Accuracy

15. 1. Measuring error = 1/10 of smallest division ii. iii. i.i. A.Measuring with a Ruler

16. What is the following measurement? 2.Practice

17. **Measure from the bottom of the meniscus B.Measuring a Liquid

18. 1.Practice i. ii.

19. iii. iv.