1. Scientific Method Use the worksheet

2. The Scientific Method What is the scientific method? – It is a process that is used to find answers to questions about the world around us.

3. Is there only one “scientific method”? – No, there are several versions of the scientific method. Some versions have more steps, while others may have only a few. However, they all begin with the identification of a problem or a question to be answered based on observations of the world around us and provide an organized method for conducting and analyzing an experiment.

4. What is a hypothesis? It is an educated guess based on observations and your knowledge of the topic.

5. What is data? It is information gathered during an experiment.

6. Sequence Identify the Problem Form a Hypothesis Create an Experiment Perform the Experiment Analyze the Data – Modify the Experiment Communicate the Results

7. Developing a Theory A hypothesis that meets the scrutiny of repeated experimentation may become a theory Theory: well-tested explanation for a broad set of observations Can not be proved – Why is this necessary? – How does this affect the public’s perception of theories?

8. Scientific Laws Describes and/or summarizes the results of many observations and experiments Different from a theory – Laws do not attempt to explain, they simply state facts What are some examples of scientific laws?

9. Using the scientific method Example Problems: – Your car won’t start – Your phone doesn’t work – Your computer won’t print Using the scientific method, develop: – At least three hypotheses that could explain your problem – An experiment to test each hypothesis – What actions you might take based on the results of your experiments

10. Chemistry the science of matter; a branch of the natural sciences; deals with: – the composition of matter – properties of matter – reactions

11. WHAT’S THE MATTER?!?! If someone asks you, " What's the matter ? " You will reply "Matter is anything that has mass and volume..."

12. Matter anything that has mass and occupies space

14. Matter can be broken down into a substance or a mixture.

15. Substances any material with a definite chemical composition – either ELEMENTS or COMPOUNDS H – hydrogen; O - oxygen or H 2 O

16. Element A chemical substance that cannot be broken down or transformed There are about 120 known elements – Hydrogen H – Carbon C – Oxygen O – Lithium Li – Sodium Na – Chlorine Cl

17. Categories of Matter The Periodic Table can be found on page 28-29 of your text book and on the inside back cover

18. Compound Two or more elements combined into one substance – Salt NaCl – Carbon Dioxide CO 2 – Hydrogen Peroxide H 2 0 2 – SugarC 6 H 12 0 6

19. Mixture a combination of two or more materials Categorized as homogenous or heterogeneous. combined physically; just mix. no new substances formed.

20. Homogeneous A homogeneous mixture has the same uniform appearance and composition throughout. – Vinegar – Shampoo – Pepsi

21. Heterogeneous A heterogeneous mixture consists of visibly different phases – Sand in water – soup – granite – salad

22. Observations The act of noting and recording something with instruments. An observation is a description of an event. Use your senses Observations help us decide how a certain variable might affect the problem

23. An observation DOES NOT… Interpret the result (this happened because we stirred the solution) Assume the conclusion (it is rust versus it looks like rust)

24. Qualitative Observation A descriptive observation – Color – Shape – Texture – Hot/cold

25. Quantitative Observation A numerical observation – Temperature – Mass – Volume

26. QualitativeQuantitative Heavy2 tons Far from earth300 light years away MicroscopicSmaller that 1 micrometer Burns quicklyBurns at a rate of 1 centimeter per minute Hot350°C

27. 2 ways that matter can be changed: 1.Physical change 2.Chemical change

28. Physical Properties of Matter can be experienced using one of the five senses or detected through any measuring device without changing the substance How it Looks (Shiny, Dull, Color, etc.) How it Feels (Hard, Soft, Rough, Smooth, etc.) How it Smells (Sweet, Sharp, Terrible, No Smell, etc.) How it Sounds (Loud, Soft, Echo, No Sound, etc.) What it Does (Bounce, Stretch, Tear, Break, Magnetism, etc.) Measurements (mass, volume, density, temperature, length, etc.)

29. Physical Change a change that does not change the chemical nature of the substance Change of state (Solid, Liquid, Gas) Examples: boiling water dissolving sugar in water cutting apples

30. Chemical Property Indicates how a substance reacts with something else Observed by reacting the substance to test its property – Flammability – Reacts with water – Reacts with acids – Doesn’t react with air

31. Chemical Change Occurs when chemical bonds are broken and new bonds are formed Signs of a chemical Change – Formation of a new substance solid precipitate – Color change – Gas is produced – Energy change (gets hot/cold) – Light is produced

32. Physical Vs. Chemical Change Burning Gasoline? Boiling Water? Breaking glass? Compression of a spring?

33. Dino Lab Objective: The package claims the dinosaur grows over 600% when placed in water. Is this claim true?

34. Measurements Length – Head to tail Height – head to foot Thickness – width under belly

35. Dino Measurement Lab Perimeter – distance around the outside of an object Area – amount of space an object takes up in two dimensions Mass – use the same balance each day

36. Volume Must use proper measuring techniques Volume: Read -on a flat surface -at eye level -from the bottom of the meniscus

37. Volume by displacement Record initial volume V i = 4.8 mL Record final volume V f = 5.6 mL Volume of the dinosaur = V f - V i = 5.6 – 4.8 = 0.8 mL

38. Density Mass ÷ Volume

39. Density Density is a physical property. – It may be used to identify a substance. Density is the amount of mass contained in a unit of volume. The states of matter differ in density: – Solids are more dense than liquids, which are more dense than gases, which are more dense than plasma.

41. THE EQUATION D =M V Density = Mass Volume

42. Examples What is the density of a piece of metal with a volume of 245 cm 3 and a mass of 612 g? What is the volume of a liquid with a density of 0.45 g/mL and a mass of 34. 24 g? D = M V = 612 g 245 cm 3 = 2.50 g/cm 3 D = M V V = M D = 34.24 g 0.45 g/mL = 76 mL

43. THE TRICK

44. Chemical Property Indicates how a substance reacts with something else Observed by reacting the substance to test its property – Flammability – Reacts with water – Reacts with acids – Doesn’t react with air

45. Chemical Change Occurs when chemical bonds are broken and new bonds are formed Signs of a chemical Change – Formation of a new substance solid precipitate – Color change – Gas is produced – Energy change (gets hot/cold) – Light is produced

46. Physical Vs. Chemical Change Burning Gasoline? Boiling Water? Breaking glass? Compression of a spring?

47. Review Chemistry is the study of matter. Matter is anything that has mass and volume. Matter can be classified. Make the flow chart. Mixtures can be separated physically. Substances come from the periodic table.

48. Scientist describe matter using: Qualitative observations Quantitative observations Physical properties and changes Chemical properties and changes

49. Create your own examples: Example Qualitative Observation Quantitative Observation Physical property Physical change Chemical property Chemical change

50. Energy The capacity to do work – Moving an object (like an electron)

51. Exothermic Release energy Energy is a product in the form of heat and/or light Reaction feels warm Reactants  Products + Energy

52. Endothermic Absorb energy Energy is a reactant Feels cold Reactants + Energy  Products