1. Measurement

2. I.Measurement A.A quantity that has both a number and a unit 1.Which is not a measurement? i.12 cm ii.134.54 iii.0.0034

3. II.The Metric System A.Standard units of measurement (SI) 1.Length = meters = m 2.Mass = kilograms = kg 3.Temperature = kelvin = K i.°C + 273 = Kelvin 4.Time = second = s 5.Substance = mole = mol

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

5. IV.Question Time A.What two things are needed in a measurement? B.What is the SI unit of measurement for length, mass, temperature, time and substance?

6. V.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

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

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

9. 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 VII.Accuracy

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

11. IX.Accuracy vs. Precision

12. A.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 X. Question Time

13. 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 XI. Percent Error error

14. 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%