Welcome Back!! Unit 1: Day 1

1. Welcome Back!!Unit 1: Day 1 1. Notes – Scientific Method 2. Independent/dependent variable practice • Due by end of class • HW: • Signed safety contract (to be turned in) - WED • Signed syllabus (keep in binder) – WED • **TYPED Lab Report – Wednesday**

2. Ch. 1: Science of Chemistrypgs 2 - 35 Burley 2013

3. Scientific Method • Scientific speculationis worthless unless it is supported by experimental evidence. • This principle led to the development of the scientific method. • The scientific method is a series of steps followed to solve problems, including collecting data, formulating a hypothesis, testing the hypothesis, and stating conclusions.

4. Parts of the Scientific Method • Ask a question • Make observations • Qualitative - descriptions • Quantitative - measurements • Do background research • Formulate hypothesis • Test by experimentation • Analyze & draw conclusion • Communicate your results

5. Inference involves a judgmentor assumption Observation uses the five senses Using the scientific method requires that one be a good observer.

6. Data Observations are also called data • There are two types of data. • Quantitative Data: • Measurements • Must have numbers • Qualitative Data: • Descriptions • No numbers

7. Hypothesis: • A theory or explanation that is based on observations and that can be tested. • They are not just a “guess.” • When scientists formulate new hypotheses, they are usually based on prior experience, scientific background knowledge, preliminary observations, and logic. • Usually, a hypothesis can be supported or refuted through experimentation or more observation. • Can be disproven, but not proven to be true.

8. Law vs. Theory • Law – a summary of many experimental results and observations; a law tells how things work. • Theory – an explanation for some phenomenon that is based on observation, experimentation, and reasoning.

9. Factors to consider in an experiment: • Independent Variable is a factor that can be varied or manipulated in an experiment. • Dependent Variable depends on the independent variable. • In a scientific experiment, you cannot have a dependent variable without an independent variable. • Experimental controls are factors in the experiment that are held constant.

10. Example 1: • A rabbit’s fur grows longer as weather gets colder. • Independent variable? • Weather gets colder • Dependent variable? • Rabbit’s fur growth

11. Example 2: • Does a person’s age affect his/her reaction time? • Independent variable? • Age • Dependent variable? • Reaction time

12. Unit 1: Day 2 • Go over worksheet • Lab Report Info • Read over info on graphs/tables • Spaghetti Lab

13. Unit 1: Day 3 1. Collect Lab Reports 2. Syllabus Check 3. Go over worksheet 4.Notes: • States of Matter • Chemical/Physical Properties 5. HW - Worksheet

14. What is Chemistry? • Everything we see everyday is made up of chemicals • Even the things we don’t see are made up of chemicals! • A chemical is any substance that has a definite composition – it’s always made of the same stuff no matter where the chemical comes from.

15. Matter • Anything that has mass and takes up space. • 3 Phases: • Solid • Liquid • Gas

16. State of Matter

17. Now you draw the types of matter: Gas Arrangement? - Far apart Movement? - Yes – fast Solid Arrangement? - Very close Movement? - Very little – vibrate only slightly Liquid Arrangement? - Close, but not touching Movement? - Yes – can flow

18. The Physical States of Matter: Solids, Liquids, and Gases Fixed – keeps shape when placed in a container. Indefinite – takes the shape of the container.

19. Properties of Matter: Physical/Chemical • Physical Properties • Determined without changing the nature of the substance • Ex: density, color, hardness • Chemical Properties • Indicates how a substance reacts with something else (anytime there is a reaction). • Ex: flammability

20. Physical vs. Chemical Properties Examples of Physical Properties Boiling point Color Slipperiness Electrical conductivity Melting point Taste Odor Dissolves in water Shininess (luster) Softness Ductility Viscosity (resistance to flow) Volatility Hardness Malleability Density (mass / volume ratio) Examples of Chemical Properties Burns in air Reacts with certain acids Decomposes when heated Explodes Reacts with certain metals Reacts with certain nonmetals Tarnishes Reacts with water Is toxic Chemical properties can ONLY be observed during a chemical reaction! Ralph A. Burns, Fundamentals of Chemistry 1999, page 23

21. Classwork/Homework: • Chemical vs Physical Properties Worksheet

22. Unit 1 Day 4: Demos! • Go over Phys/Chem Properties wkst • Demos! • Need Books @ break • Physical/Chemical Change • Worksheet using book/notes

23. Chemical Reactions • Chemical Reactions: The process by which one or more substances change to produce one or more different substances. • 2 Parts: • Reactant – a substance or molecule that participates in a chemical reaction. • Product – a substance that forms in a chemical reaction.

24. Physical & Chemical Changes • Physical Changes • Identity of a substance DOES NOT change. • Things to look for: • Change of state • Changes in arrangement • Changes in speed • Location • Examples?

25. Physical & Chemical Changes (con’t) • Chemical Changes • Identity of a substance DOES change. • Things to look for: • Evidences of chemical reactions:

26. Evidence for Chemical Changes: • Evolution of a gas • Formation of a precipitate • Release or absorption of energy • Heat / light / sound • Color change • Examples of chemical reactions???

27. Unit 1 Day 5: Goals for Today • NEED BOOKS!! • Check/go over phys/chem changes wkst • Classification Activity • Classifying Matter • Work on Flow Chart Using p21-27 - check and go over • CW/HW: Substances vs. Mixtures Worksheet (both sides)

28. Matter • Anything that has mass and takes up space

29. Atom • The smallest unit of an element that still maintains the properties of the element

30. Molecule • Consists of two or more atoms bonded together in a definite ratio • Can be either elements or compounds

31. Classifying Matter • Pure Substances – matter that has definite chemical and physical properties. • Chemically combined • Examples: Compounds& elements

32. Element • Pure substance that contains only one kind of atom • A substance that cannot be separated or broken down into simpler substances by chemical means • Examples?

33. Compound • Pure substance that is composed of two or more kinds of atoms joined by chemical bonds • Examples?

34. Classifying Matter • Mixtures – a combination of 2 or more substances NOT chemically combined. • They can be separated by physical means • Examples: • Italian Dressing • Sand and Water • Sugar water

35. 2 Types of Mixtures • Homogeneous • mixture that has uniform structure or composition throughout • Examples: • Sugar Water • Salt Water • Coffee • Heterogeneous • Not evenly mixed –different regions of the mixture have different chemical properties • Examples: • Italian dressing • Soil and water • Milk

36. Please Work on:1. Flow Chart Using pgs.21-27 2. Substances vs. Mixtures wkst

37. Classification of Matter MATTER (gas. Liquid, solid, plasma) Separated by PURE SUBSTANCES MIXTURES physical means into Separated by COMPOUNDS ELEMENTS HOMOGENEOUS MIXTURES HETEROGENEOUS MIXTURE chemical means into Kotz & Treichel, Chemistry & Chemical Reactivity, 3rd Edition , 1996, page 31

38. Unit 1 Day 6: • Metric System • Dimensional Analysis • Practice!! • CW/HW: Worksheet • Ch 1 Test next Thursday! • Lab tomorrow! Bring goggles & notebooks!

39. Volume • The space that the object occupies • Measurement • Solids (l × w × h) • Liquids (graduated cylinders)

40. Mass • The quantity of matter contained in the object • Measured using balances • DOES NOT change with gravity

41. Weight • The force produced by gravity acting on mass • DOES change with gravity

42. Metric System • System of measurement based on 10 • Common Base Units • Length: measures distance between 2 points • Meters – m • Mass: measure amount of matter in an object • Grams – g • Volume: measures abount of space an object occupies • Liter – L • Or L x W x H = m3 • Prefixes

43. SI Base Units

44. SI Prefixes

45. Conversion Factor • A ratio that is derived from the equality of two different units and that can be used to convert from one unit to the other • Examples? • Hint:

46. Dimensional Analysis • In chemistry, you often need to convert a measurement from one unit to another, this is done by using a conversion factor, and by the method of dimensional analysis.

47. Dimensional Analysis Practice • 1. Convert 360 g to mg

48. Dimensional Analysis Practice 2. 0.00238 cg to grams:

49. Dimensional Analysis Practice 4. 0.014 kg to cg:

50. CW/HW: Worksheet • Ch 1 Test next Thursday! • Lab tomorrow! Bring goggles & notebooks!