1. Chapter 1. Section 2: The Way Science Works Critical thinking helps you solve problems logically.

2. Scientists use scientific methods to solve problems.

3. The scientific method involves critical thinking in that it entails thinking about a problem and making objective judgments about the results.

4. Laws & Theories In science, a law is a summary of many experiments, results and observations. A law only describes what happens, not why it happens. A law also predicts the results of experiments not done yet.

5. An explanation of why things work the way they do is called a theory. A theory explains the results of many kinds of experiments and observations. Theories are always open to challenges and testing.

6. Remember: A hypothesis is an educated guess based on accurate and relevant information. A law is a summary of experimental results and observations and tells us what will happen (but doesn’t explain why). A theory is an explanation that can be used to predict what will happen in new situations.

7. Units of Measurement Scientists use standard units of measure that together form the International System of Units, or SI. SI stands for the French term le Système Internationale d’Unités.

8. SI Units SI units give consistency.

9. SI Units UnitSymbolQuantity MetermLength KilogramkgMass SecondsTime AmpereA Electric current Molemol Amount of substance Candelacd Luminous intensity KelvinKTemperature Derived units: Area, Volume, Density

10. Metric Units King Henry Died ____ Drinking Chocolate Milk Kilo hecto deca ____ deci centi milli 100010010Base101001000

11. Metric Conversions 1.85 m = ______ cm 7 m = _______ cm 1.6 kg = ______ g 2800 mg = _____ g

12. Bellwork 8/20/14 How many miles will a person run during a 10K race? (1 km =.621 miles) A family pool holds 10,000 gallons of water. How many m 3 is this? (264.2 gal = 1 m 3) How many seconds are in 1 year? …hmmm Pepsi puts 355 ml of soda in a can. How many drops is this? (20 drops = 1mL)

13. Derived Units Area, in m 2, is the size of a 2-dimensional surface Volume is the amount of space a substance occupies Units in m 3 or cm 3 or liters (L).

14. g/cm 3 g/mL Density 1.A sample of 1.A sample of aluminum has a volume of 15.0 mL and weighs 40.5 g. What is its density? 2.Calculate the density of sulfuric acid if 35.4 mL of the acid weighs 65.14 g. 3.What is the density of CO gas if 0.196 g occupies a volume of 100 ml?

15. 4.A block of wood 6 cm on each side has a mass of 217 g. What is the density of the block? (Hint, don’t forget to find the volume of the wood.) 5. 100 grams of a liquid completely fill a 200 mL bottle. What is the density of the liquid? 6. A solution has a density of 1.50 g/mL. How many grams are needed to obtain 10.0 mL of solution?

16. 7. What is the mass of the ethyl alcohol that exactly fills a 200.0 mL container? The density of ethyl alcohol is 0.789 g/mL. 8.If a 96.5g piece of aluminum has a density of 2.7 g/cm 3, what is its volume? 9. 100 grams of a liquid completely fill a 200 mL bottle. What is the density of the liquid?

17. 9. Chloroform is a liquid with a sticky sweet odor that was once used as a surgical anesthetic. If the density of chloroform is 1.49 g/cm 3, what is the volume of 25 g of chloroform? 10. If a 96.5g piece of aluminum has a density of 2.7 g/cm 3, what is its volume?

18. Section 3: Organizing Data Key Ideas Why is organizing data an important science skill? How do scientists handle very large and very small numbers? How can you tell the precision of a measurement?

19. Charts & Graphs

20. Scientific Notation t = distance from Earth to Neptune (m) speed of light (m/s) t = 4,500,000,000,000 m 300,000,000 m/s OR… t = 4.5 10 12 m 3.0 x 10 8 m/s

21. When should you use scientific notation? To express really large or really small numbers 10 3 1000 10 2 100 10 1 10 10 0 1 10-10.1 10 -2 0.01 10 -3 0.001

22. Scientific Notation 602 200 000 000 000 000 000 000 atoms 5280 = 5.28 x 10 3 0.0821 = 8.21 x 10 -2 5280 = 5.28 x 10 3 0.0821 = 8.21 x 10 -2

23. Scientific Notation 0.00235 m 46000 cows 112 pm 0.760 µg

24. Use scientific notation to make calculations. (2.3 x 10 5 ) x (5.2 x 10 4 ) = (2.3 x 10 -5 ) x (5.2 x 10 -4 ) =

25. (2.3 x 10 5 )= (5.2 x 10 4 ) = (5.2 x 10 4 ) (2.3 x 10 -5 )

26. Use Scientific Notation to make calculations The adult human heart pumps about 18,000 L of blood each day. Write this value in scientific notation. Your county plans to buy a rectangular tract of land measuring 5.36 x 10 3 m by 1.38 x 10 4 m to establish a nature preserve. What is the area of this tract?

27. Accuracy vs. Precision

28. Accuracy & Precision Accuracy is a description of how close a measurement is to the actual/true value. – This was hitting the basket! Or hitting a bullseye. Precision is the exactness of a measurement(repeatable). – This was hitting in the same place more than once.

30. Precision in Measurements Scientists use significant figures to show the precision of a measured quantity. They are the uncertain part of the measurement. Significant figures tell you how precise a measurement is.

31. cm

34. Significant Figures Scientists use significant figures to show the estimated part of measurements. The number of figures tells us the precision of the measurement. 4.13612.78.5347.9567

35. Remember this rule: The number of sig figs is the number of sig figs in the least precise measurement.

36. Significant Figures Practice Time! Round the following to the number of sig figs in the parentheses: 7.376 (2 sig figs)362.306 (5 sig figs) 0.5234 (2 sig figs).2395 (3 sig figs)

37. Here are more! Write the answers in the correct number of sig figs. 15.75 m x 8.45 m = (3) 5,650 L ÷ 27 min = (2)

38. Calculate the volume of a room that is 3.125 m high, 4.23 m wide and 5.75 m long. Write the answer with the correct number of sig figs. Find the area of a rectangle that is 8.5 cm long and 3.45 cm wide. Round your answer to the correct number of significant figures.