1. The Metric System Chapter 1 Le Systeme Internationale d’Unites

2. 7 Base Units  meter (m)  kilogram (kg)  second (s)  ampere (A)  kelvin (K)  mole (mol)

3. meter  distance  ruler, meter stick  based on light in a vacuum (space)  previously a Pt bar

4. kilogram  mass  balance  originally based on the mass of 1 liter of water  now, a piece of Pt-Ir

5. second  time  clock, stopwatch  based on the radiation emitted by Cs  formerly, based on the solar day and the tropical year

6. kelvin  temperature  thermometer  based on the triple point of water temperature and pressure at which a substance can exist as a solid, liquid, and gas!

7. mole  amount  6.022 x 10 23 or 602200000000000000000000  always measured indirectly!  based on carbon-12  must specify what is being counted (ions, atoms, electrons, etc.)

8. prefixes  (d) deci-  (c) centi-  (m) milli-  () micro-  (n) nano-  (p) pico-  (f) femto-  (a) atto-  (da) deka-  (h) hecto-  (k) kilo-  (M) mega-  (G) giga-  (T) tera-  (P) peta-  (E) exa-

9. Conversions 3.1 kilograms to milligrams  starting amount x non-prefix unit x final unit starting unit non- prefix unit  3.1 kg x 10 3 g x 1 mg = 3100000 mg 1 kg 10 -3 g

10. Practice Problems  Convert the following masses to the units requested. 0.765g to kilograms 1.34g to milligrams 34.2mg to grams 23,745kg to milligrams

11. Answers to practice problems.765g x (1kg/1000g) =  0.000765kg or 7.65 x 10 -4 kg 1.34g x (1000mg/1g) =  1340mg or 1.340 x 10 3 mg 34.2mg x (1g/1000mg) =  0.0342g or 3.42 x 10 -2 g 23,745kg x (1000g/1kg) = 23,745,000g 23,745,000g x (1000mg/1g) =  23,745,000,000mg or 2.3745 x 10 10 mg

12. Scientific Notation…

13. What is it?  A shorter way to express very large or very small numbers.  Preserves accuracy and precision of the number.

14. Format 5.34 x 10 4 significand fancy word for these digits order of magnitude how big or small the number is this number is always between one and ten

15. So what does it mean?  The order of magnitude (“exponent”) is the number of places the decimal point moves to determine the “regular” notation.  A positive order of magnitude indicates that the decimal moves to the right.  A negative order of magnitude indicates that the decimal moves to the left.

16. Example 5.34 x 10 4 =5.3400 =53400. 5.34 x 10 -4 =0005.34 =.000534

17. Converting from Scientific Notation  A positive exponent means move the decimal to make the number bigger: 1.243 x 10 6 = 1243000. moved decimal 6 places  A negative exponent means move the decimal to make the number smaller: 7.968 x 10 -5 =.00007968 moved decimal 5 places

18. Converting to Scientific Notation  The decimal always goes after the first non- zero digit from the left: 1243000 = 1.243 x 10 ??.00007968 = 7.968 x 10 ??  Big numbers have positive exponents and small numbers have negative exponents: 1243000 = 1.243 x 10 6 moved decimal 6 places.00007968 = 7.968 x 10 -5 moved decimal 5 places

19. DENSITY  Density: the mass of an object divided by its volume…it is a physical property.  Density = Mass Volume  D = M/V  Units: Mass is always in GRAMS Volume is in cm 3 or mL because 1cm 3 = 1mL (REMEMBER THIS)

20. Calculate the Density for the Following 1. The mass of a piece of aluminum is 1.20g and the volume is 0.44cm 3. What is the Density of the piece of Aluminum? 2. Calculate the density of a piece of metal if its mass is 201.0g and its volume is 18.9cm 3.

21. Density answers 1. D = M / V D = 1.20g / 0.44cm 3 D = 2.72g/cm 3 2. D = M / V D = 201.0g / 18.9cm 3 D = 10. 6g/cm 3

22. Different Types of Density Problem  If you are given the Density and volume and asked to solve for the Mass… Mass = Volume x Density M = V x D  If you are given the Density and Mass and asked to solve for the Volume… Volume = Mass / Density V = M / D

23. Different Density Problems 1. The density of CCl 4 is 1.58g/mL. What is the mass of 95.7mL of CCl 4 ? 2. What is the volume of 227g of olive oil if its density is 0.92g/mL?

24. Answers to Different Density Probs 1. M = V x D M = 95.7mL x 1.58g/mL M = 151g or 1.51 x 10 2 g 2. V = M / D V = 227g / 0.92g/mL V = 246.74mL or 2.4674 x 10 2 mL

25. Accuracy & Precision  Accuracy refers to how close a measurement is to the true or accepted value  Precision refers to the reproducibility of a measurement

26. Accuracy & Precision Think of a dartboard: Precise but not accurate Precise & accurate Not precise or accurate