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Why We Use What We Use

Why We Use What We Use. Book Chapter 2A. Chemistry objectives to be covered. Differences between physical and chemical properties and changes Differences between metals, nonmetals, and metalloids History of the Periodic table Arrangement of the Periodic Table.

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Why We Use What We Use

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  1. Why We Use What We Use Book Chapter 2A

  2. Chemistry objectives to be covered • Differences between physical and chemical properties and changes • Differences between metals, nonmetals, and metalloids • History of the Periodic table • Arrangement of the Periodic Table

  3. How to use the Periodic Table to predict the personality of a given element • The Physical Properties of Elements that demonstrate patterns within the Periodic Table • Electron configuration and how it can be used to predict how an atom will act chemically

  4. Introduction 1. Why is the Statue of Liberty made of Copper Plates? Why is Gold used for the wiring in the Space Shuttle? Why is hydrogen and oxygen gases used as Rocket Fuel? • all these substances are used because they have the perfect properties for what they need to be used?

  5. 2. What are physical properties again? Give examples. • Ways in which we can describe a substance without changing what it is • Odor • Does it conduct heat well • color

  6. Does it conduct electricity well

  7. Phase of Matter, Melting Point

  8. Metallic Malleability-does it bend easily

  9. Malleability

  10. Luster of Metals

  11. 3. What are chemical properties? Give examples • Ways in which we can describe how a substance acts when introduced to other substances • How does it react with water • How does it react with an acid

  12. Does it react with air to form a rust

  13. Properties Make the Difference 4. What is the difference between Physical and Chemical changes? physical change: change in mass or volume or density but not a change in what it is, physical changes are always reversible chemical change: something new is formed, with completely different properties, it is not reversible!

  14. Properties Make the Difference Chemical or Physical Property? a. some metals become dull when exposed to air b. Mercury’s high density and liquid state at room temperature makes it useful in barometers c. Metals, when pure, have a high luster(are shiny and reflect light) d. Archaeologists, uncover ancient golden artifacts, that are untarnished, while iron artifacts are often corroded

  15. e. the hardness of diamonds enable them to be used as drill bits • f. Metals are typically ductile(can be drawn into a wire) • g. You shouldn’t use silver utensils to handle sulfur containing foods such as eggs and mustard, since the silver will tarnish • h. The high melting point of Tungsten makes it useful for light bulb filaments • i. Metals are typically much better conductors of heat and electricity than are non metals • j. The Magnesium ribbon of a photo flashcube ignites in oxygen around it when you snap a picture

  16. Properties Make the Difference 5. What are two reasons why a superior substance may not be used to do a certain job? • a. it might be too expensive or unavailable • b. undesirable chemical and physical properties may overshadow the desirable ones 6. Why is Zinc being used today for copper pennies? • it is less expensive and just as hard as copper, its density is close to copper

  17. Properties Make the Difference 7. Zinc pennies were also used during WWII. Why were they not used later? • Zinc corrodes much faster than Copper, it is higher up on the Activity Series! 8. How was the problem solved in modern times? • Zinc pennies are coated with Copper

  18. Zinc coated pennies

  19. The Chemical Elements 9. How many elements are known today? • 117 10. Of those, how many are important to us on a daily basis? • about 40

  20. The Chemical Elements 11. What are the two major classifications of elements? • metals and non metals 12. Why are they classified the way they are? • metals have very similar chemical and physical properties that differ substantially from the properties of nonmetals

  21. The Periodic Table 13. How many elements had been discovered by the mid 1800’s? • 60(5 gases H, O, N, F, Cl, 2 liquids-Br and Hg) 14. Who was the first to publish what became known as the Modern Periodic Table? • Dimitri Mendeleev in 1869

  22. Dimitri Mendeleev

  23. Example of Mendeleev predictions for Germanium- Ekasilicon Property Predicted Observed atm mass 72 72.59 Density 5.5 5.3 form of oxide EsO2 GeO2 D of oxide 4.7 4.2 Form of Cl EsCl4 GeCl4 D of Cl 1.9 1.8

  24. The Periodic Table 15. What does the Periodic Table function like? • a calendar 16. What 2 properties did he use to construct his Table? • their atomic masses and the way they reacted with other elements

  25. The Periodic Table 17. How were the Atomic Masses of the elements determined? • they gave Carbon a value of 12 and then they compared all the other masses to it 18. What elements did these early chemists look to for helping them figure out how elements combined? • most things combine with O and Cl so they are what the chemists used

  26. Do Grouping the Elements on Page 101

  27. Pattern of Atomic Numbers 19. PT showed that some elements had similar properties, but what did it not answer? • Why? 20. What are all atoms composed of? • Protons(+), electrons(-), and neutrons

  28. Pattern of Atomic Numbers 21. What is the only distinguishing feature of any element? • # of protons, it is the only thing that will ID an element 22. What is another name for # of protons? • Atomic Number = Z

  29. Pattern of Atomic Numbers 23. Where can the atomic number be found on the Periodic Table? • it is the whole number on top of each element symbol 24. What is the Z of Na? F? Mg? H? Ti? 25. How is the modern Periodic Table arranged? • by increasing Atomic number

  30. Pattern of Atomic Numbers 26. What aspect of Z really determines how an element will act? • it is the electrons, in a neutral atom, Z = electrons as well 27. What are the horizontal rows on the Periodic Table called? • Periods 28. How many horizontal rows are there?

  31. Pattern of Atomic Numbers 29. How are they designated? • by number( Period 1, Period 2...) 30. What are the vertical columns called? • Groups or Families

  32. Pattern of Atomic Numbers 31. How are they designated? • either by a special name give a long time ago or by the name of the first element in the Group • Li Group: Alkali metals • Be Group: Alkaline metals • F Group: Halogens • He Group: Noble or Inert(unreactive) Gases

  33. Pattern of Atomic Numbers 32. What is the Periodic Law? • when you order elements according to increasing atomic number(number of protons) the chemical and physical properties will repeat themselves 33. What can the position of the element on the Periodic Table tell you? • how reactive an element is

  34. 34. What is it about an element that makes it reactive? • how many electrons it has in its outer shell 35 . What is a shell? • electron can be thought of as existing in shells or layers around the nucleus

  35. What determines Properties 36. What is another name for these shells? • energy levels 37. How many energy levels do elements have? • it depends on how big it is, Energy levels will always equal the Period #

  36. What determines Properties 38. How many energy levels do Li, Zr, Pb, U, and Cl have? • Li=2, Zr=5, Pb=6, U=7, Cl = 3 39. What are subshells? • areas with energy levels where electrons live

  37. What determines Properties 40. How many subshells are there? • 4 they are called s, p, d, and f 41. How many electrons can live in s? • 2 42. How many electrons can live in p? • 6

  38. What determines Properties 43. How many electrons can live in d? • 10 44. How many electrons can live in f? • 14 45. What is the electron configuration? • it is a map of the location of all the electrons in an element

  39. Electron Configuration 46. What is the electron configuration for the first 11 elements? 47. What is the electron configuration for Pb, Cr, Br, U? 48. How can you determine the outer shell electrons? • add up the total number of s and p electrons in the highest energy level of an element

  40. Electron Configuration 49. Why are these so important? • they are farthest away from the influence of the nucleus so they are the ones that will be lost or gained in order for the element to become more stable 50. What makes an atom stable? • if it has 8 electrons, full s and p, in the outer shell

  41. Electron Configuration 51. What makes the alkali and alkaline metals so reactive? • they only have 1 or 2 electrons in the outer shell, so they will want to get rid of them in order to lose they entire outer shell and their new “outershell” is now complete 52. What makes the halogen nonmetals so reactive? • they want to gain one electron to complete their 8

  42. Electron Configuration 53. What makes the noble gases so unreactive? • they already have a full 8 electrons in their outer shell(except for He who only needs 2)

  43. Periodic Properties 54. What are periodic properties? • properties of the element that repeat themselves as you go down or across the chart 55. Give an example of this • metals tend to become more reactive as you go down a family or group • nonmetals tend to become more reactive as you go up a family or group

  44. Periodic Properties 56. What are some periodic properties • ionization energy, electronegativity, atomic radius, and ionic radius 57. What is atomic radius? • the distance from the nucleus to the outermost electron

  45. Periodic Properties 58. What happens to radius as you go down a group and why? • it increases, because you are adding a brand new energy level 59. What happens to radius as you go across a period and why? • in decreases, the electrons are all in the same shell, but the nucleus is getting bigger drawing them in

  46. Periodic Properties 60. What is ionization energy? • amount of energy needed to knock away the outermost electron 61. What happens to IE as you go across a period? Why? • it increases because the atoms are getting smaller, therefore closer to the nucleus

  47. Periodic Properties 62. What happens to IE as you go down a group and why? • it decreases because the atoms are getting bigger therefore farther away from the nucleus, therefore harder for the nucleus to hold on 63. What is electronegativity? • how attractive an nucleus is to the electron of another atom

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