1. Scientific Notation Significant Figures Conversion Factors

2. Scientific Notation Measurements made in chemistry often involve very large or small numbers. To express these numbers conveniently, scientific notation is used. In scientific notation, numbers are expressed in terms of their order of magnitude.

3. Scientific Notation For example 54 000 can be expressed as 5.4 x 10 4 in scientific notation, and the number 0.000 008 765 can be expressed as 8.765 x 10 -6.

4. As the preceding examples show, each value expressed in scientific notation has two parts. The base is always between 1 and 9.99 (less than 10)

5. To write the first factor of the number, move the decimal point to the right or left so there is only one nonzero digit to the left of it. Examples 5467 0.004389

6. The second part is raised to an exponent of 10. The exponent is determined by counting the number of places the decimal point must be moved. If the decimal point is moved to the left, the exponent is positive. If the decimal point is moved to the right, the exponent is negative.

7. Examples Express each of the following in scientific notation. 67 000 6.7 x 10 4

8. Examples 890 000 000 8.9 x 10 8 0.000 000 000 000 009 8 9.8 x 10 -15

9. Examples 805 000 8.05 x 10 5 0.000 004 5 4.5 x 10 -6

10. Examples Express each of the following in standard form. 8.2 x 10 3 1.5 x 10 -6 8200 0.000 001 5

11. Examples 1.775 x 10 7 7.065 x 10 -5 17 750 000 0.000 070 65

12. Example 3.86 x 10 6 3 860 000

13. Significant Figures Whenever you make a measurement there is always some uncertainty associated with it, due to the nature of the object and / or the instrument.

14. Significant Figures For any measurement, the number of significant figures that can be reported is the number of figures that can be read accurately from the measuring device plus one more figure that can be estimated.

15. Significant Figures Significant figures let other people know just how good the measurement is!

16. Sig Fig Rules 1) All digits 1 – 9 inclusive are significant. Example: 129 has 3 significant figures

17. Sig Fig Rules 2) Zeros between significant digits are always significant. Example: 5 007 has 4 significant figures

18. Sig Fig Rules 3) Trailing zeros in a number are significant only if the number contains a decimal point. Example: 100.0 has 4 significant figures 100 has 1 significant figure 100. has 3 significant figures

19. Sig Fig Rules 4) Zeros in the beginning of a number whose only function is to place the decimal point are not significant. Example: 0.0025 has 2 significant figures.

20. Sig Fig Rules 5) Zeros following a decimal significant figure are significant. Example: 0.000470 has 3 significant figures 0.47000 has 5 significant figures

21. Do Not Count Sig Figs When Using standardized values Or Molar Mass from the periodic table

22. Conversion Factors A conversion factor is a ratio derived from the equality between two different units that can be used to convert from one unit to the other! Remember that solving a chemistry problem is like taking a trip.

23. Ask yourself Where am I? Where am I going? How am I going to get there?

24. Conversion Factor Examples

25. More Examples

26. Examples 1 kilogram = 1000 g

27. Use conversion factors to convert each of the following 1.612 dollars to quarters 1 dollar = 4 quarters

28. 2. 537 dollars to nickels 1 dollar = 20 nickels 537 dollars x

29. 3.7 days to minutes Double Conversion!!!!!! 1 day = 24 hours 1 hour = 60 minutes

30. 4.177 millimeters to meters 1 millimeter = 0.001meter

31. 5.32 kilograms to milligrams Double Conversion!!! 1 kilogram = 1000 grams 1 milligram = 0.001 gram

32. 6. 3.4 liter to milliliters 1 millimeter = 0.001 meter 1 milliliter = 0.001 liter 3.4 liter x 3400 mL

33. Assignment Now take out your practice problems.