1. Units and Measurement Chemistry Mrs. Coyle

2. A) SI Units, Scientific Notation, Measurement, Accuracy, Precision, Error

3. Science and Units Math- the language of Science SI Units – International System Length -Meter m Temperature - Celsius C Mass – Kilogram kg Time – seconds s National Bureau of Standards

4. Accuracy - a measure of how close a measurement is to the true value of the quantity being measured.

5. Example: Accuracy Who is more accurate when measuring a book that has a true length of 17.0cm? Susan: 17.0cm, 16.0cm, 18.0cm, 15.0cm Amy: 15.5cm, 15.0cm, 15.2cm, 15.3cm

6. Precision – a measure of how close a series of measurements are to one another. A measure of how exact a measurement is.

7. Example: Precision Who is more precise when measuring the same 17.0cm book? Susan: 17.0cm, 16.0cm, 18.0cm, 15.0cm Amy: 15.5cm, 15.0cm, 15.2cm, 15.3cm

8. Example: Evaluate whether the following are precise, accurate or both. Accurate Not Precise Not Accurate Precise Accurate Precise

9. Error Error= experimental –accepted value

10. Significant Figures The significant figures in a measurement include all of the digits that are known, plus one last digit that is estimated.

11. Centimeters and Millimeters

12. Graduated Cylinder - Meniscus

14. Significant Figures When the decimal is present, start counting from the left. When the decimal is absent, start counting from the right. Zeroes encountered before a non zero digit do not count.

15. Counting Numbers Counting numbers have infinite significant figures. Ex: 3 apples

16. Base SI Units QuantityUnitSymbol Lengthmeterm Masskilogramkg TemperaturekelvinK Timeseconds Amount of Substancemolemol Luminous Intensitycandelacd Electric Currentamperea

17. Derived SI Units (examples) QuantityunitSymbol Volumecubic meterm3m3 Densitykilograms per cubic meterkg/m 3 Speedmeter per secondm/s Newtonkg m/ s 2 N EnergyJoule (kg m 2 /s 2 )J PressurePascal (kg/(ms 2 )Pa

18. Units for Volume m 3 cm 3 dm 3 L Liter mL 1 dm 3 = 1L 1cm 3 = 1mL

19. Temperature A measure of how hot or how cold an object is. SI Unit: the kelvin ( K ) Note: not a degree Absolute Zero= 0 K

20. Temperature Scales

21. Celsius and Kelvin K= o C + 273

22. Farenheit and Celsius o F= (1.8 o C ) +32