The Enterprise of Chemistry

1. The Enterprise of Chemistry Chapter 1

2. What is Chemistry? • The study of the structure, properties of matter and the changes that they can undergo.

3. Everything in your life is related to chemistry

4. Everything in your life is related to chemistry • Life processes are chemical processes

5. Everything in your life is related to chemistry • Life processes are chemical processes • Chemistry is considered the central science because it overlaps so many other sciences.

6. Chemists solve problems

7. Chemists solve problems • Engineers, Hair stylists, Archeologists, Pharmacists, Perfume manufacturers, Forensic Investigators, etc….

8. Chemistry allows you to look at the world around you in a new way. • It helps you understand why things occur the way they do.

9. There is a close relationship between the properties of matter (how it behaves) and the structure of matter (how it is put together)

10. There is a close relationship between the properties of matter (how it behaves) and the structure of matter (how it is put together) • Example: Diamonds • They are very hard because of the way its atoms are held together

11. Chemists can also develop new structures

12. Chemists can also develop new structures • These are called synthetic materials

13. Chemists can also develop new structures • These are called synthetic materials • Example: Nylon • Developed from studies of the properties of silk

14. Chemists can also develop new structures • These are called synthetic materials • Example: Nylon • Developed from studies of the properties of silk • Nylon is similar to silk in structure and behavior

15. 1.2 Homework Pg. 6 1-4

16. The Scientific Method • A way of answering question about the world we live in.

17. Steps in the Scientific Method • Observation • Question/Problem • Hypothesis • Experiment • Data Collection • Conclusion • Retest

18. Observations • Gathered through your senses • A scientist notices something in their natural world

19. Observations • An exampleof an observation might be noticing that many salamanders near a pond have curved, not straight tails

20. Question/Problem • The observation leads to a question. • Because science is driven by curiosity this step may come first.

21. Hypothesis • A suggested solution to the problem. • Must be testable • Sometimes written as If…Then… statements • Predicts an outcome

22. Hypothesis • An example of a hypothesis might be that the salamanders have curved tails due to a pollutant in the moist soil where they live.

23. Experiment • A procedure to test the hypothesis.

24. Experiment Variable – factor in the experiment that is being tested

25. Experiment A good or “valid” experiment will only have ONE variable!

26. Scientific Experiments Follow Rules • An experimenter changes one factor andobserves or measureswhat happens.

27. The Control Variable • The experimenter makes a special effort to keep other factors constant so that they will not effect the outcome. • Those factors are called control variables.

28. What is the Purpose of a Control? • Controls are NOT being tested • Controls are used for COMPARISON

29. Other Variables • The factor that is changed is known as the independent variable. • The factor that is measured or observed is called the dependent variable.

30. Example of Controls & Variables • For example, suppose you want to figure out the fastest route to walk home from school. • You will try several different routes and time how long it takes you to get home by each one. • Since you are only interested in finding a route that is fastest for you, you will do the walking yourself.

31. What are the Variables in Your Experiment? • Varying the route is the independent variable • The time it takes is the dependent variable • Keeping the same walker throughout makes the walker a control variable.

32. One more thing… it is best to make several trials with each independent variable.

33. Remember: To be a Valid Experiment: • Two groups are required --- the control & experimental groups • There should be only onevariable

34. Data • Results of the experiment • May be quantitative (numbers) or qualitative

35. Data • Must be organized • Can be organized into charts, tables, or graphs

36. Conclusion • The answer to the hypothesis based on the data obtained from the experiment

37. Retest In order to verify the results, experiments must be retested.

38. Natural Law • After a number of experiments, the results are summarized into a natural law. • Which describes how nature behaves but does not explain why it behaves that way.

39. Theory • Finally, scientists may be able to formulate a theory. • A theory explains why nature behaves in the way describe the natural law. • I answer the original question, and also any other question that were raised during the process.

40. Solving a Problem 1)Identify a Problem 2) State Observations about the problem 3) Form a Hypothesis about the problem (if…then…) 4) Design an Experiment to test the hypothesis 5) Collect Data and form a conclusion 6) Retest and summarize results in a Natural Law 7) Formulate a Theory

41. Laws and Theories • Natural law draws together many observations and the results of many experiments into a “big picture.” • It does not explain what the picture means.

42. Laws and Theories • A Theory provides the explanation for the “big picture.” • Think of a theory as a “super-hypothesis” • Theories can be wrong even after all the work that went into the experiment. • Theories are open to revision

43. 1.3 Homework Pg. 13 1-4 Practice Problems Pg. 11 1,2

44. 1. Listen to or read instructions carefully before attempting to do anything. 2. Wear safety goggles to protect your eyes from chemicals, heated materials, or things that might be able to shatter. 3. Notify your teacher if any spills or accidents occur. General Safety Rules

45. 4. After handling chemicals, always wash your hands with soap and water. 5. During lab work, keep your hands away from your face. 6. Tie back long hair. General Safety Rules

46. 7. Roll up loose sleeves. 8. Know the location of the fire extinguisher, fire blanket, eyewash station, and first aid kit. 9. Keep your work area uncluttered. Take to the lab station only what is necessary. General Safety Rules

47. 10. It is suggested that you wear glasses rather than contact lenses. 11. Never put anything into your mouth during a lab experiment. 12. Clean up your lab area at the conclusion of the laboratory period. 13. Never “horse around” or play practical jokes in the laboratory. General Safety Rules

48. 1. Chipped or cracked glassware should not be used. Show it to the teacher. 2. Broken glassware should not be disposed of in a classroom trashcan. There is a special glass disposal container for it. 3. When pouring liquids into glassware, make sure the container you are pouring into is resting on a table at least a hands breadth from the edge. Glassware Safety

49. 4. Pour down a glass stirring rod to prevent liquids from splattering. 5. If a piece of glassware gets broken, do not try to clean it up by yourself. Notify the teacher. 6. When inserting glass tubing into a rubber stopper, apply a lubricant like glycerin to the glass and use a twisting motion. Glassware Safety

50. 7. Do not place hot glassware in water. Rapid cooling may make it shatter. Glassware Safety