1 / 72

Bellwork

Bellwork. Chapter Pre-test: 1. What instrument would you use to measure temperature? Thermometer 2. Which of the following is a unit of volume? A. atmosphere B. gram C. meter D. liter D. 3. What characteristic of matter can you measure using a graduated cylinder? Volume

ryu
Télécharger la présentation

Bellwork

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Bellwork • Chapter Pre-test: • 1. What instrument would you use to measure temperature? Thermometer • 2. Which of the following is a unit of volume? • A. atmosphere • B. gram • C. meter • D. liter D. • 3. What characteristic of matter can you measure using a graduated cylinder? Volume • 4. The sides of a cube are 2 cm by 2 cm. What is the volume of the cube? 8 cm3 • 5. What additional quantity would you need to calculate the density of the cube in question 4? Mass • 6. Which of the following topics is not studied in chemistry? • A. Composition of matter • B. reactions of substances • C. properties of materials • D. motion of large objects. D.

  2. Physical science Chapter 2 Properties of Matter

  3. Lab • Groups of three-four will be made • Each group will be provided 5 materials, a rubber band, a steel paper clip, a copper prong, wooden pencil or toothpick, and a graphite pencil filler. • Determine the properties or characteristics of the materials by touching, smelling, and looking at them. • Record these properties in a table/chart. • After you record these properties, write a description of each material that could be used to clearly identify it.

  4. Bellwork • Finish the lab quickly so we can discuss your descriptions.

  5. Possibilities • Rubber’s elasticity • Copper’s color • Steel’s shininess • Wood’s brittleness • Graphite’s ability to leave a mark • Description: • Copper is a gold-ish solid that is flexible enough to be shaped and bent

  6. Section objectives • 1. Classify pure substances as elements or compounds. • 2. Understand why are elements and compounds are classified as pure substances • 3. Understand how mixtures differ from pure substances. • 4. Know what the main difference is among solutions, suspensions, and colloids.

  7. Intro • Your book uses the example of a care label on your clothes. • Why is it there? • A tendency to wrinkle is a property of cotton, the tendency to not wrinkle is a tendency of polyester, the tendency to shrink when washed is a property of wool. • They all have different properties because they have different compositions. • These compositions can be broken into pure substances and mixtures

  8. Pure substances • Matter that always has the same composition is classified as a pure substance, or substance • Every sample of a given substance has the same properties because a substance has a fixed, uniform composition. • Salt is a composition of sodium and chloride • Substances can be classified into two categories, elements and compounds

  9. Elements • There are only about 100 elements • Element: a substance that cannot be broken down into simpler substances • An atom is the smallest particle of an atom • An element has a fixed composition because it contains only one type of atom.

  10. Elements • No two elements contain the same type of atom. • Most elements are solids at room temperature (20 C, 68 F)

  11. Examples • Aluminum

  12. Example • Carbon

  13. Elements • Some elements are gas at room temperature • Oxygen and nitrogen are the main gases we breathe

  14. Bellwork • Draw the diagram classifying the different types of matter • What are elements made of? • What form are most elements in at room temperature?

  15. Liquid Elements • Only two elements that are liquid at room temperature: Bromine and mercury, both are very poisonous

  16. Symbols • The symbols for elements are similar to why scientists use the SI system of measurement. • Many symbols are based on the Latin name for the element and all scientists agree on the symbol for each element • *project!: Choose an element you are unfamiliar with. Research the origin of the symbol. Then, research the application or use of the element. Write at least a paragraph detailing this information and turn it in on Thursday

  17. Compounds • Someone read the first paragraph under Compounds on pg. 40 • A compound is a substance that is made from two or more simpler substances. The simpler substances are either elements or other compounds

  18. Compounds continued • THE PROPERTIES OF A COMPOUND DIFFER FROM THOSE OF THE SUBSTANCES FROM WHICH IT IS MADE • Water is a compound made up of the elements hydrogen (H) and oxygen (O) • Both of these elements are gases at room temperature, but water is a liquid • Hydrogen can fuel a fire and oxygen is needed to keep it going, but water is used to put it out

  19. COMPOUNDS • COMPOUNDS ALWAYS CONTAIN TWO OR MORE ELEMENTS JOINED IN A FIXED PORTION • Silicon dioxide, for example, is the compound found in most light colored sand • It is made from the elements silicon ( a gray solid) and oxygen. • It is always made with two oxygen atoms for each silicon atom. (di means 2) Same for water

  20. Mixtures • Mixtures tend to retain some of the properties of their individual substances • But the properties of a mixture are less constant than the properties of a substance • The properties of a mixture can vary because the composition of a mixture is not fixed.

  21. On your own • Read pages 41-44 • Create a chart with descriptive visuals and examples to help you classify the different types of mixtures • Heterogeneous • Homogeneous • Solutions • Suspension • Colloid • When you finish, complete section 1 in your workbook

  22. Types of mixtures • Mixtures are combinations of substances • The composition of the substances (unlike compounds) are not constant • Example: salsa • Heterogeneous mixtures: the parts that make up the mixture are noticeably different • Example: sand

  23. Bellwork • Think of a homogeneous and a hetergeneous mixture

  24. Heterogeneous MixturesHetero (different) genus (kind)

  25. Homogeneous mixtures • Homogeneous mixtures: the substances are so evenly distributed that it is difficult to distinguish one substance from another • Example: a stainless steel spoon is a homogeneous mixture of iron, chromium and nickel

  26. Homogeneous Mixtures

  27. Solutions, Suspensions, Colloids • Based on the size of its largest particles, a mixture can be classified as a solution, suspension, or a colloid

  28. Solution • Solution: when substances dissolve and form a homogeneous mixture • Example: sugar dissolved in water • Characteristics: • Particles are too small to settle out of the solution • Particles cannot be trapped by a filter • Particles are too small to scatter light

  29. Solution

  30. Suspension • “Shake Well” • Suspension: a heterogeneous mixture that separates into layers over time • Example: Sand and water • Characteristics: • Particles will settle • Particles can be filtered • Particles are large enough to scatter light

  31. Suspension

  32. Colloid • Colloid: contains some particles that are intermediate in size between the small particles in a solution and the larger particles in a suspension. • Example: homogeneous milk • Characteristics: • Particles do not separate into layers • You cannot filter to separate parts of a colloid • Particles are large enough to scatter light

  33. Colloid

  34. Bellwork 8-29 • Give an example of a solution, suspension, and a colloid

  35. Examples of physical properties • Physical property: any characteristic of a material that can be observed or measured without changing the composition of the substances in the material. • Viscosity • Conductivity • Malleability • Hardness • Melting point • Boiling point • Density

  36. Viscosity • Viscosity: the tendency of a liquid to keep from flowing-its resistance to flowing • The greater the viscosity the slower the liquid flows

  37. Viscosity • Viscosity usually decreases when heated • Importance? Think motor oil…

  38. Conductivity • Conductivity: a material’s ability to allow heat to flow • Materials with high conductivity (metals) are conductors • If a material is a good conductor of heat it will usually do the same for electricity • So why do we stir soup with a wooden spoon?

  39. Conductive materials

  40. Malleability • Malleability: the ability of a solid to be hammered without shattering. • Most metals are malleable • Solids that shatter when struck are brittle • Give an example of a malleable and brittle material.

  41. Malleability

  42. Hardness • Hardness: how hard a material is • To compare hardness you can try to scratch one object with another • Diamond is the hardest material known

  43. Hardness

  44. Melting and boiling points • Melting Point: The temperature at which a substance changes from a solid to liquid • Boiling Point: The temperature at which a substance boils • What are the melting and boiling points of water in Celsius? • Are there any factors that can affect boiling point?

  45. Melting/Boiling Points

  46. Density • Density: can be used to test the purity of a substance • Examples include methanol for bike racing

  47. Using Physical Properties to Identify Materials • 1. Decide which properties to test • 2. Perform tests on unknown samples • 3. Compare data results with data reported for known materials • Example: crime investigation

  48. Using Properties to Choose Materials • Properties determine which materials are chosen for which uses. • Wood shoelaces?

More Related