Get Hand Outs—next 2 projector Mini Quiz #1 9/2/09

1. Get Hand Outs—next 2 projectorMini Quiz #19/2/09 • What are four materials that you will need for this class?

2. WednesdaySeptember 2nd, 2009 It is time to take some notes…

3. Chemistry & Measurement

4. Introduction… • Chemists use tools like pipettes to accurately measure liquids. • Some pipettes can be used to accurately measure liquids to tenths, even hundredths of a milliliter. • Careful measurement is vital in scientific investigations. • In Unit 1 you will learn about the nature of science and… • You will also learn how scientists make and record measurements.

5. Introduction… CHEMISTRY Nature of Science Scientific Method Qualitative observations Quantitative Observations Scientific Notation Accuracy & Precision Certainty & Significant Figures Measurement Units & Conversions

6. Big Goals for Learning • To describe science and the scientific method. • To compare qualitative and quantitative observations. • The express numbers in scientific notation • To express accuracy, precision and certainty • To use the rules for significant figures in calculations • To use metric prefixes and conversion factors • To work with units of density and other derived units

7. Objectives • define chemistry • identify qualitative and quantitative observations • list the main steps in the scientific method • describe the nature of science

8. Key Terms • Chemistry— • Matter— • Mass— • Volume— • Chemist— • Qualitative— • Quantitative—

9. Chemistry & the Nature of Science • Science is a system of knowledge about the natural world. • It is also a way of improving and increasing that knowledge. • Latin “scientia” means “to have knowledge”. • Chemistry is one field of science along with field of biology, astronomy, zoology, ecology, etc.

10. Chemistry & the Nature of Science • Chemistry is the study of matter and how it changes. • Matter is anything that has mass and volume. • Mass is a measure of how much matter an object contains. • Volume is the amount of space and object takes up. • Matter is all around you… • The air you breathe, the juice you had for breakfast and you, to name a few.

11. Chemistry & the Nature of Science • Chemists are scientists who study matter and its changes. • They do so with two different types of observations. • Qualitatively, they look and the object; its shape, color, hardness, viscosity, odor, etc. • Quantitatively, they take measurements of the substance to determine its volume, temperature, mass, etc.

12. Chemistry & the Nature of Science • Besides studying the characteristics of a substance, chemists want to know how the substance changes. • Does it react, or combine with, other substances. • How is it that hydrogen gas combines with oxygen gas to make liquid water? • This is the beginning of what chemists do…question their surroundings!

13. Rules of the Lab • Use an indoor voice only to the people in your lab group. Do not wander from table to table. • There is no unauthorized work in the lab. • Use the equipment according to instructions. • Wear protective clothing such as a lab apron. Always wear shoes in the lab. Chemical splash goggles are required when you are working in the lab. • Avoid loose clothing or dangling jewelry; tie back long hair when an open flame is in use. • Always dispose of chemicals in the specified manner. Do not use the drain indiscriminately. • Treat the lab with respect.

14. Mini Quiz #29/3/09 No Worksheets HW: Work on Poster Board • Name the lab equipment quiz... • After the Mini Quiz  Get into lab groups and select a leader ASAP...the leader needs to come see Mr. Holt as soon as he/she is elected.

15. Into the Lab we Go! • In your group, you need to elect a leader, reader, artist, labeler. • The leader is to make the lab run smoothly, • know what is going on and keep everyone on task. • If anyone in the group is slacking, it is the leader’s job to get them back on task. • Ultimately if the team fails, the leader fails. • Only the leader may speak with Mr. Holt.

16. Into the Lab we Go! • The reader’s job is to read the question to the group. • They are also supposed to read the index cards throughout the room to the group. • The reader may not speak with Mr. Holt at any time during the lab 

17. Into the Lab we Go! • The artist’s job is to design the blueprint for the poster board. • They may ask the group for ideas but they are not required to. • The leader may force the artist to work with the group. • The artist may not speak with Mr. Holt at any time during the lab  • As you travel from station to station, it is the artist’s job to make sure everyone understands each index card.

18. Into the Lab we Go! • The labeler’s job is to come up with the “balloons” of descriptions on the poster board. • They may ask the group for ideas but they are not required to. • The leader may force the labeler to work with the group. • The labeler may not speak with Mr. Holt at any time during the lab  • The labeler must design a name sheet for the group with a team name, team members and a logo. • The labeler must carry this around with the team.

19. Into the Lab we Go! • The goal of the lab group is to divide up tasks, but work as a team. • Every member of the group must answer the questions of the handout and they must be able to answer any questions Holt may have about the lab or lab equipment. • The only time a group member other than the leader can speak to Mr. Holt is if he asks you a question.

20. More Key Terms • Scientific method— • Hypothesis— • Variable— • Independent variable— • Dependent variable— • Theory— • Technology—

21. The Scientific Method • Science is a system of knowledge. • It is based on observations about the natural world. But it is more than that. • It is also a process of learning about the natural world. • Scientists use a process called the scientific method to answer questions or solve problems. • They try to explain why matter behaves like it does.

22. The Scientific Method • The scientific method is a way of improving and increasing existing knowledge based on existing facts and ideas, new observations and reason or logic.

23. The Scientific Method • The process can vary quite a bit but it often involves the following steps: • Observe the natural world. • Ask a question or state a problem based on observations. • State a hypothesis based on facts—a hypothesis is a possible explanation based on facts and reason. It predicts what might happen.

24. The Scientific Method • Test the hypothesis by designing and performing experiments. • The qualitative and quantitative observations made during experiments are called data or results. • Analyze the results. • This means organizing the data, looking for patterns and making sense of the data.

25. The Scientific Method • Share the results and conclusions with others stating whether the experimental data supported the hypothesis or not. • If not, what things might you add or change in the experiment or hypothesis to bring us closer to truth. • Scientists share their findings in published journals so that scientist all over the world can read and reproduce their experiments comparing results and checking for errors.

26. Experimenting • In many experiments, certain conditions or characteristics of matter are measured or controlled. • These are variables. • Variables may change during an experiment or they may be held constant. • Volume, temperature, type of substance and time are all variables.

27. Mini Quiz #3 (9/8/09) • Get hand out of HW problems... • Then for our Mini...name the piece of glassware...from this site: • http://www.sciencegeek.net/Chemistry/taters/labequipment.htm • Copy down my blog site...there will be info placed here throughout the year. • http://blogs.muskegonisd.org/mholt

28. Experimenting • Some experiments are designed to see how one variable changes when another variable is changed. • The variable that is changed by the experimenter is the independent variable. • The other variable is the dependent variable—it responds to the independent variable.

29. Example Under lamp for 2 hours Under lamp for 3 hours Under lamp for 1 hour After the time goes by the chemist measures the volume of water that remains after evaporation… Independent variable = time, dependent variable = volume of water that evaporates due to the changing time under the heat lamps

30. Which is Which? • A chemistry student is trying to determine what factor will make 2.0g of salt crystals dissolve the quickest. He tells you that his teacher gave him a poor grade on his set up. He tells you his set up and it is your job to help him fix it. This is what he did... • He took 2.0g of salt crystals and put them into 100mL of 30ºC water and let it dissolve. He recorded the time that it took to dissolve all the crystals. Then he took 2.0g of salt crystals and put them into 500mL of 80ºC water and stirred the solution. • What would you suggest...write up your plan.

31. Which is Which? • Possible set up... • Get three beakers of 200mL of distilled water—two beakers at 30ºC and the 3rd at 80ºC. • Into the first beaker dump 2.0g of salt crystals in and record the time to dissolve. This is the control and all the other tests should be based around this one. • To the 2nd beaker...add the 2.0g of salt and stir it with a spoon until all the salt has dissolved. Record the time. • Then to the 3rd beaker...add the 2.0g of salt and do not stir—let the salt dissolve and record the time.

32. Which is Which? • The independent variable is the variable that the chemist changes. In test #2, what is the independent variable? • The dependent variable is the variable that changes because the chemist change something from the control. What is the dependent variable in the 2nd test? • What is the independent variable in the 3rd test? • What is the dependent variable in the 3rd test?

33. Analyzing • One way to analyze the results of an experiment is to make a graph. • The relationship between the two variables can be seen on the graph. • The independent variable is plotted on the x-axis and the dependent variable on the y-axis.

34. Other Stuff to Know • Experiments cannot prove that a hypothesis is correct. • However, scientists perform the experiments many times. • Each time new results support the hypothesis, the hypothesis become more likely. • If the results of many experiments support the hypothesis, scientists may call this hypothesis a theory. • A theory is a well-tested hypothesis that is widely accepted.

35. Other Stuff to Know • An example is the atomic theory of matter. • It explains matter in terms of atoms and the tiny particles that make up atoms: protons, neutrons and electrons. • Many experiments have supported the idea that matter is made of these tiny particles.

36. The Science of Nature • People of all cultures have been observing and studying the world for many centuries. • Because of this, the body of scientific knowledge continues to grow and change. • A new discovery may change an existing theory. • New results may give meaning to old observations. • New tools may measure or show something for the first time. • As the process of science answers one question, it leads to many new questions.

37. The Science of Nature • When scientific knowledge is used in a practical way to improve lives, the result is called technology. • For example, if a chemist comes up with a drug that slows a human disease, that development is called technology. • Scientists generally do not focus on ways to apply what they learn. • Instead, engineers apply scientific knowledge and create technology.

38. Mini Quiz #4 (09/09/09) • List and identify all of the qualitative (QL) and quantitative (QT) observations… • On the 3rd day of September I was working in the lab with 5.0g of a white, crystalline solid. My teacher asked me to place it in 250mL of a clear liquid with no odor. I measured and recorded the mass of the liquid to be 250g. When I placed the solid in the liquid I noticed that the solid dissolved. When I placed the beaker on the scale it now read 255.0 g.

39. Objectives • Write a number in scientific notation • Convert a number in scientific notation to standard notation • Give examples of accurate measurements and precise measurements • Know how the quality of a measuring tool affects certainty • Identify the significant figures in a measured value

40. Key Terms • Scientific notation— • Superscript— • Accuracy— • Precision— • Significant figure—

41. Scientific Notation • Scientists often have to measure very large amounts or very small amounts. • To make it easier to work with, they write numbers in scientific notation. • Scientific notation is a shortcut that uses powers of 10. • Powers of 10 are written as 10x, where x is a number called and exponent. • The exponent is shown as a superscript, a number written just above the writing line. • The exponent tells how many times 10 is multiplied by itself. (103 = 10 x 10 x 10 = 1000)

42. Scientific Notation • There is an easy way to express a number in scientific notation. • Just move the decimal point in the given number to create a number that is between 1 and 10. • For example 3,470,000 the decimal is moved from behind the last zero to be in between the 3 and the 3 to get 3.47.

43. Scientific Notation • Another…0.00000567 the decimal is moved to go in between the 5 and the 6 to make 5.67. • Next count the number of places you moved the decimal point and that is your power of 10… • Example 1, the decimal was moved 6 places and example 2, the decimal was moved 6 placed. • When the number greater than 1, the exponent is positive, when it is less than 1 the exponent is negative. So… • Example 1 = 3.47 x 106 • Example 2 = 5.67 x 10-6

44. Example • Write the number 765,000,000,000 in scientific notation. • 7.65 • Moved the decimal 11 places • Number is greater than 1 so… • 7.65 x 1011 • Try 0.000000349 • 3.49 x 10-7 • Write 3.2 x 10-4 in standard notation • 0.00032

45. Objectives • Give examples of accurate measurements & precise measurements • Know how the quality of a measuring tool affects certainty • Identify the significant figures in a measured value

46. Key Terms • Accuracy— • Precision— • Significant figure—

47. Accuracy, Precision and Certainty • Are some measurements better than others? • Do measuring tools affect measurement? • Does it matter how measurements are written down?

48. Accuracy, Precision and Certainty • In science it is important to make measurements that are both accurate and precise. • Accuracy is how close a measurement is to the correct or accepted value. • Precision is how close a measurement is to other measurements of the same thing.

49. Accuracy, Precision and Certainty • Dart board analogy of accuracy and precision.

50. Accuracy, Precision and Certainty • Scientists work carefully to obtain accurate and precise measurements. • Scientists also need to know how certain their measurements are. • After measuring something, scientists record the measurement as a number. • In any number that represents a measurement, there are digits that are certain and one digit that is uncertain. • The last digit on the right in the number is an estimate, or best guess. • This digit is the uncertain one.