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Wk05 lec cl1823 chemistry of non metals

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CL1823 Chemistry of non metals

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Wk05 lec cl1823 chemistry of non metals

  1. 1. Non metals <ul><li>Objectives </li></ul><ul><li>To learn the Properties, biological importance and applications of </li></ul><ul><li>Carbon </li></ul><ul><li>Nitrogen </li></ul><ul><li>Oxygen </li></ul><ul><li>Phosphorus </li></ul><ul><li>Halogens </li></ul>
  2. 2. Carbon A. Symbol denoted as ‘C’ <ul><li>Every carbon atom contains : </li></ul><ul><li>six protons (atomic numbers) </li></ul><ul><li>six or more neutrons (depending on the isotopes) </li></ul><ul><li>six electrons </li></ul>C 12 6 symbol Atomic number Mass number
  3. 3. Carbon B. Isotopes <ul><li>Three naturally occurring isotopes: </li></ul><ul><li>Carbon-12, carbon-13 and carbon-14 </li></ul><ul><li>carbon-12 most abundant – 98.99% in nature </li></ul><ul><li>carbon-13 – 1% in nature </li></ul><ul><li>carbon-14 - radioactive </li></ul>6 neutrons 7 neutrons 8 neutrons C 12 6 C 13 6 C 14 6
  4. 4. Carbon C. Bonding <ul><li>Carbon has 6 electrons in total –check your periodic table. These electrons are placed at spaces that are called electron shells. Of the 6 electrons, only 2 electrons can place at the inner shell and the other 4 at the outer shell. So, it is said that carbon has 4 valence electrons (Valence electrons is the number of electrons in the outer most shell.) </li></ul><ul><li>Carbon needs 4 more electrons at the outer most shell to be stable (atoms with 8 electrons in the outer most shell are considered stable). </li></ul><ul><li>How could carbon atom find the other 4 electrons? It is through forming covalent bonds. 2 electrons make one covalent bond. Covalent bond is formed when 2 atoms share electrons together in which each bonding atom contributes 1 electron. </li></ul><ul><li>In this figure, the black, pink & red dots are electrons </li></ul><ul><li>Each carbon atom (with 4 valence electrons) form bonds with the other 4 atoms (i.e. 3 H atoms and 1 C atom) to achieve 8 valence electrons. </li></ul><ul><li>In conclusion, carbon forms 4 covalent bonds to be stable. </li></ul>
  5. 5. Carbon D. Allotropes <ul><li>Definition : different physical forms of the same element </li></ul><ul><li>Allotropes differ in the way: </li></ul><ul><li>the atoms are bonded with each other </li></ul><ul><li>the atoms are arranged into a structure </li></ul><ul><li> different physical and chemical properties. </li></ul>
  6. 6. Carbon D. Allotropes <ul><li>Three types for carbon: </li></ul><ul><li>Diamond </li></ul><ul><li>Graphite </li></ul><ul><li>3. Buckminsterfullerene </li></ul>C60
  7. 7. Carbon D. Allotropes – diamond 1. Colourless 2. Hard – hardest substance known to man 3. Cut diamonds sparkle brilliantly
  8. 8. Carbon D. Allotropes – diamond <ul><li>Structure: </li></ul><ul><li>Each carbon atom bonds tetrahedrally to four other carbon atoms to form a three-dimensional lattice. (carbon atom is depicted as black dot in this diagram) </li></ul><ul><li>In this 3-D lattice, all 4 valence electrons of carbon are used for bonding, thus, there are no free mobile electrons to conduct electric current (electrical insulator) </li></ul>
  9. 9. Carbon D. Allotropes – graphite <ul><li>Black </li></ul><ul><li>Soft </li></ul>Eg. pencils!!
  10. 10. Carbon D. Allotropes – graphite <ul><li>Structure: </li></ul><ul><li>Each carbon atom bonds to three other carbon atoms to form planar (flat) layers. (carbon atom is depicted as black dot in this diagram) </li></ul><ul><li>Each planar layer is made up of rings containing six carbon atoms </li></ul><ul><li>In this planar layers, 3 out of 4 valence electrons of carbon are used for bonding, thus, 1 electrons in each carbon atom is free to move and conducts electric current (electrical conductor) </li></ul>
  11. 11. Carbon D. Allotropes – graphite Bonds between carbon atoms within a layer of graphite are strong, but the forces between the layers are weak As the layers can slip past each other, graphite is soft and can be used as a lubricant
  12. 12. Carbon D. Allotropes – buckministerfullerene <ul><li>Discovered in 1985 </li></ul><ul><li>Specific structure : </li></ul><ul><li>60 carbon atoms bond in 20 six-membered rings and 12 five-membered rings (like a football). </li></ul><ul><li>Called bucky ball or buckministerfullerene or fullerene </li></ul>
  13. 13. Carbon E. Occurrence found in the following forms : i. Elemental form eg. graphite, diamond ii. As carbon dioxide in the air and water (most importantly to living organisms) CO 2
  14. 14. Carbon E. Occurrence iii. Wood from plants wood is made of a very large carbohydrate, called cellulose, which consists of many glucose molecules. Glucose are made up of carbon, hydrogen and oxygen.
  15. 15. Carbon E. Occurrence <ul><li>Fossil fuels , eg. coal, petroleum, and natural gas. </li></ul><ul><li>Macromolecules: carbohydrates, fats, and proteins: all are based on carbon. </li></ul>
  16. 16. Carbon The human body is about 18 percent carbon by mass F. Biological Importance Cell membranes are made up of lipids, which are large organic molecules of carbon, hydrogen, oxygen, nitrogen and phosphorous.
  17. 17. Carbon F. Biological Importance Proteins Made up of amino acids with carbon, hydrogen, nitrogen and oxygen atoms
  18. 18. Carbon F. Biological Importance gigantic carbon-based molecules that contain the genetic information for a living organism. Ribonucleic acids (RNA) and deoxyribonucleic acids (DNA) :
  19. 19. Carbon G. Application <ul><li>Carbon is added to make steel from iron, purify metals, and add strength to rubber. </li></ul><ul><li>Carbon compounds as fuels </li></ul><ul><li>As jewellery – diamond rings </li></ul><ul><li>To identify age of compound with C-14 – known as carbon dating </li></ul>
  20. 20. Nitrogen denoted as ‘N’ A. Symbol <ul><li>In nature, every nitrogen atom contains : </li></ul><ul><li>seven protons </li></ul><ul><li>seven or more neutrons (depending on which isotope) </li></ul><ul><li>seven electrons. </li></ul>N 14 7 symbol Atomic number Mass number
  21. 21. Nitrogen B. Isotopes Two naturally occurring isotopes: Nitrogen-14 : 99.6 %, Nitrogen-15 : 0.4 % Artificial isotopes: N-12, N-13, N-16, N-17, N-18, N-19, N-20 7 neutrons 8 neutrons N 14 7 N 15 7
  22. 22. Nitrogen C. Bonding <ul><li>Nitrogen has 7 electrons in total –check your periodic table. Of the 7 electrons, only 2 electrons can place at the inner shell and the other 5 at the outer shell. So, nitrogen has 5 valence electrons. </li></ul><ul><li>Thus, nitrogen atom needs 3 more electrons to be stable. It forms 3 covalent bonds to achieve 8 electrons in the outer most shell. </li></ul><ul><li>In this figure, the black & pink dots are electrons </li></ul><ul><li>Each nitrogen atom (with 5 valence electrons –pink dots) form bonds with the other 3 atoms (i.e. 3 H atoms) to achieve 8 valence electrons. </li></ul><ul><li>In conclusion, nitrogen forms 3 covalent bonds to be stable. </li></ul><ul><li>Note: the 2 pink dots are the 2 electrons that do not involve in bond formation. They are called the “lone pair”. </li></ul>
  23. 23. Nitrogen D. Properties <ul><li>Gaseous element that makes up the largest portion of the earth's atmosphere. </li></ul><ul><li>Colourless </li></ul><ul><li>Odourless </li></ul><ul><li>Tasteless </li></ul><ul><li>Non toxic </li></ul><ul><li>Melts at -210.01°C; boils at -195.79°C </li></ul>
  24. 24. Nitrogen E. Preparation fractional distillation of liquid air (liquid nitrogen has a lower boiling point than liquid oxygen) nitrogen distils off first and can be collected.
  25. 25. Nitrogen F. Biological importance <ul><li>Important component of : </li></ul><ul><li>Bases (DNA, RNA) </li></ul><ul><li>Proteins </li></ul><ul><li>Cell Membrane </li></ul>
  26. 26. Nitrogen F. Biological importance Nitrogen is an important element in plant nutrition. It is available to the plants in the form of nitrate. Bacteria in the soil convert atmospheric nitrogen into a nitrate, that can be absorbed by plants, a process called nitrogen fixation .
  27. 27. Nitrogen G. Application fractional distillation of liquid air Nitrogen Ammonia chemical products nitrous oxide (N 2 O) (fertilizers, nitric acid) (laughing gas) As starting material to make other products
  28. 28. Nitrogen G. Application nitrous oxide (N 2 O) (laughing gas) Mixed with oxygen and used as an anaesthetic to ease pain in some types of surgery The use of nitrous oxide in the olden days
  29. 29. Nitrogen G. Application Liquid nitrogen is also used as a coolant to store biological samples eg. cells, tissues.
  30. 30. Oxygen A. Symbol denoted as ‘O’ <ul><li>In nature, every oxygen atom contains: </li></ul><ul><li>eight protons </li></ul><ul><li>eight or more neutrons (isotopes) </li></ul><ul><li>eight electrons. </li></ul>O 16 8 symbol Atomic number Mass number
  31. 31. Oxygen B. Isotopes Three naturally occurring isotopes of oxygen: O-16 : 99.76 % O-17 : 0.04 % O-18 : 0.2 % Artificial isotopes: O-14, O-15, O-19, O-20, O-21, O-22 8 neutrons 9 neutrons 10 neutrons 16 8 O 17 8 O 18 8 O
  32. 32. Oxygen C. bonding <ul><li>Oxygen has 8 electrons in total –check your periodic table. Of the 8 electrons, only 2 electrons can place at the inner shell and the other 6 at the outer shell. So, oxygen has 6 valence electrons. </li></ul><ul><li>Thus, oxygen atom needs 2 more electrons to be stable. It forms 2 covalent bonds to achieve 8 electrons in the outer most shell. </li></ul><ul><li>In this figure, the black & pink dots are electrons </li></ul><ul><li>Each oxygen atom (with 6 valence electrons –pink dots) form bonds with the other 2 atoms (i.e. 2 H atoms) to achieve 8 valence electrons. </li></ul><ul><li>In conclusion, oxygen forms 2 covalent bonds to be stable. </li></ul><ul><li>Note: the 4 pink dots without association with H atoms are the 4 electrons that do not involve in bond formation. They are called “lone pair”. </li></ul>
  33. 33. Oxygen D. Allotropes <ul><li>Ordinary oxygen O 2  two atoms per molecule </li></ul><ul><li>Ozone O 3  three atoms per molecule </li></ul><ul><li>3. Tetraoxygen O 4  four atoms per molecule, readily breaks down into ordinary oxygen </li></ul>
  34. 34. Oxygen E. Properties <ul><li>On earth, oxygen is more abundant than any other element </li></ul><ul><li>Colourless </li></ul><ul><li>Odourless </li></ul><ul><li>Tasteless </li></ul><ul><li>Non toxic </li></ul><ul><li>melts at -218.4° C, boils at -182.96° C </li></ul>Oxygen is everywhere Rock & sand = SiO 2 Ocean = H 2 O
  35. 35. Oxygen F. Preparation fractional distillation of liquid air (liquid nitrogen has a lower boiling point than liquid oxygen) nitrogen distils off first (not collected) followed by oxygen which is collected liquid O 2 (higher bp) liquid N 2 (lower bp)
  36. 36. Oxygen F. Preparation By electrolysis of water to split the water molecules into hydrogen and oxygen.
  37. 37. Oxygen G. Biological importance <ul><li>Important component of : </li></ul><ul><li>DNA, RNA </li></ul><ul><li>Proteins </li></ul><ul><li>Cell Membrane </li></ul><ul><li>Oxygen comprises 60 percent (2/3) of the human body </li></ul><ul><li>Almost all plants and animals, including humans, require oxygen to maintain life. </li></ul>
  38. 38. Oxygen H. Application 1. Large amounts of oxygen are used in high-temperature welding torches
  39. 39. Oxygen H. Application 2. Oxygen is administered to patients who have breathing difficulty and fighter jet pilots
  40. 40. Oxygen H. Application 3. Liquid oxygen is used as rocket fuel. Oxygen gas cooled pale blue liquid O 2
  41. 41. Phosphorus A. Symbol denoted as ‘P’ <ul><li>In nature, every phosphorus atom contains: </li></ul><ul><li>15 protons </li></ul><ul><li>16 neutrons </li></ul><ul><li>15 electrons </li></ul>P 31 15 symbol Atomic number Mass number
  42. 42. Phosphorus B. Isotopes Phosphorus mostly exist as one form in nature: P-31 : 100 % Artificial isotopes: P-29, P-30, P-32, P-33
  43. 43. Phosphorus C. Bonding <ul><li>Phosphorus has 15 electrons in total –check your periodic table. Of the 15 electrons, only 2 electrons can place at the inner shell (1 st shell) and 8 electrons at the 2 nd shell and the other 5 at the outer shell. So, phosphorus has 5 valence electrons. </li></ul><ul><li>Thus, phosphorus atom needs 3 more electrons to be stable. It forms 3 covalent bonds to achieve 8 electrons in the outer most shell. </li></ul><ul><li>In this figure, the black & pink dots are electrons </li></ul><ul><li>Each phosphorus atom (with 5 valence electrons –pink dots) form bonds with the other 3 atoms (i.e. 3 F atoms) to achieve 8 valence electrons. </li></ul><ul><li>In conclusion, phosphorus forms 3 covalent bonds to be stable. </li></ul><ul><li>Note: the 2 pink dots are the 2 electrons that do not involve in bond formation. They are called the “lone pair”. </li></ul>P F F F
  44. 44. Phosphorus D. Allotropes <ul><li>The three common allotropes of phosphorus: </li></ul><ul><li>White phosphorus </li></ul><ul><li>Red phosphorus </li></ul><ul><li>Black/ violet phosphorus </li></ul>
  45. 45. Phosphorus D. Allotropes: White phosphorus <ul><li>Exist as P 4 molecule in a tetrahedral arrangement </li></ul><ul><li>Tetrahedral arrangement of P 4 causes ring strain thus, white phosphorus is not stable – ignite at 30 °C </li></ul><ul><li>It is a waxy transparent solid </li></ul>white phosphorus Structure of P4
  46. 46. Phosphorus D. Allotropes: red phosphorus <ul><li>Formed when white phosphorus is heated between 230°C and 300° C in the absence of air. </li></ul><ul><li>Much more stable compared to white phosphorus </li></ul><ul><li>3. Does not ignite spontaneously </li></ul><ul><li>4. It sublimes (passes from the solid state directly to the gaseous state) at 416° C </li></ul>
  47. 47. Phosphorus D. Allotropes: black/ violet phosphorus <ul><li>Made by heating white phosphorus at 200° C at very high pressure </li></ul><ul><li>2. Not very common compared to the white and red phosphorus </li></ul>
  48. 48. Phosphorus F. Biological importance 1. Important component of : - DNA, RNA - Proteins - Cell membrane <ul><li>The element is important in plant and animal physiology and is a constituent of all animal bones, in the form of calcium phosphate </li></ul><ul><li>Part of ATP (Adenosine triphosphate) </li></ul>
  49. 49. Phosphorus G. Application 1. Phosphorus combines readily with oxygen to form oxides P 2 O 3 reducing agent P 2 O 5 drying agent
  50. 50. Phosphorus G. Application <ul><li>The bulk of phosphorus-containing compounds are used as fertilizers. </li></ul><ul><li>White phosphorus is used in the making of rat poison </li></ul><ul><li>Red phosphorus is used in matches </li></ul>
  51. 51. Halogens General characteristics Halogens
  52. 52. Na + Cl Na + Cl –     Chlorine gaining one electron to form chloride anion, Cl - General characteristics <ul><li>Halogens are fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), Astatine (At) – Elements in Group 7 of the periodic table. </li></ul><ul><li>Halogens have 7 valence electrons, meaning that at the outermost shell of halogen atoms, there are 7 electrons. </li></ul><ul><li>To achieve 8 electrons in the outer most shell, halogens accept one electron from other atom. (i.e. halogen gains an electron ) </li></ul>Example: Halogens _ Before transfer of electron: Na atom and Cl atom After transfer of electron: (1 electron transferred from Na to Cl) Na + ion and Cl - ion            
  53. 53. <ul><li>Halogens exist as diatomic molecules under room temperature. </li></ul><ul><li>e.g F 2 , Cl 2 , Br 2 (X 2 or X-X) </li></ul><ul><li>:F:F: :Cl:Cl: :Br:Br: </li></ul>Halogens : : : : : : : : : : : :
  54. 54. Chemical properties: <ul><li>Highly electronegative, </li></ul><ul><li> Eg. F: most electronegative element </li></ul><ul><li>Good oxidizing agents, </li></ul><ul><li>Eg. Cl 2 as a bleaching agent </li></ul>Halogens
  55. 55. Physical properties: <ul><li>At room temperature and 1 atm pressure, </li></ul><ul><li>I 2 is a solid, </li></ul><ul><li>Br 2 is a liquid, </li></ul><ul><li>Cl 2 and F 2 are gases. </li></ul><ul><li>I 2 Violet-black Crystal </li></ul><ul><li>Br 2 Reddish-brown Liquid </li></ul><ul><li>Cl 2 Yellow-green Gas </li></ul><ul><li>F 2 Pale Yellow Gas </li></ul>Halogens
  56. 56. Chemical properties: <ul><li>All halogens form stable diatomic molecules with hydrogen, eg HCl, HBr and HI </li></ul><ul><li>Prepared by reaction with the salt of the halogen: </li></ul><ul><li>CaF 2(s) + H 2 SO 4(l) 2HF (g) + CaSO 4(s) </li></ul><ul><li>2NaCl (s) + H 2 SO 4(l) 2HCl (g) + Na 2 SO 4(s) </li></ul>Halogens
  57. 57. Halogen: Fluorine! <ul><li>Symbol: F </li></ul><ul><li>Too reactive to be found in nature in its diatomic form </li></ul><ul><li>Occur in the minerals as fluorite or calcium fluoride (fluorspar - CaF 2 ) </li></ul>
  58. 58. Halogen: Fluorine <ul><li>Atomic number: 19 </li></ul><ul><li>No. of protons: 9 </li></ul><ul><li>No. of electrons: 9 </li></ul><ul><li>No. of neutrons: 10 </li></ul>
  59. 59. Halogen: Fluorine <ul><li>Produced commercially from fluorspar at the rate of thousands of tons a year </li></ul><ul><li>It is shipped as a liquid in special containers, cooled by liquid air </li></ul>Preparation:
  60. 60. Halogen: Fluorine Applications: <ul><li>About ¾ of F 2 produced in USA is used for processing uranium for nuclear power plants </li></ul>
  61. 61. Halogen: Fluorine Applications: <ul><li>Small quantities of fluorine can retard the occurrence of tooth cavities </li></ul><ul><li>Sodium fluoride is added to the public water supplies to prevent tooth decay </li></ul>
  62. 62. Halogen: Fluorine Applications: <ul><li>Fluorine is used to produce Teflon. </li></ul><ul><li> Teflon is used as: </li></ul><ul><li>i. non-stick coatings on frying pans </li></ul><ul><li>ii. cabling materials </li></ul><ul><li>iii. semi-conductor manufacturing </li></ul><ul><li>iv. pharmaceutical & biotechnological manufacturing </li></ul>
  63. 63. Halogen: Fluorine Applications: <ul><li>Freon (a fluorocarbon compound) is used in refrigerants and formerly in aerosol cans as propellant causes destruction in the ozone layer! </li></ul>
  64. 64. Halogen: Fluorine Applications: <ul><li>Hydrofluoric acid, HF, dissolves glass! </li></ul><ul><li>Used for etching designs on glass </li></ul>
  65. 65. Halogen: Chlorine <ul><li>Symbol: Cl </li></ul><ul><li>Atomic Number: 17 </li></ul><ul><li>Mass number: 35 </li></ul><ul><li>No. of protons: 17 </li></ul><ul><li>No. of electrons: 17 </li></ul><ul><li>No. of neutrons: 18 </li></ul><ul><li>Isotopes: Cl-35 (75%), Cl-37 (25%) </li></ul>Symbol:
  66. 66. Halogen: Chlorine Preparation: <ul><li>Produced mainly by electrolysis of either molten or aqueous sodium chloride </li></ul><ul><li>2NaCl(aq) + 2H 2 O(l)  H 2 (g) + Cl 2 (g) + 2NaOH(aq) </li></ul><ul><li> </li></ul>
  67. 67. Halogen: Chlorine Applications: <ul><li>Manufacture of plastics - C 2 H 3 Cl is used in making polyvinyl chloride (PVC) plastics </li></ul>
  68. 68. Halogen: Chlorine Applications: <ul><li>bleaching agent - used for bleaching wood pulp for paper industry and cotton and linen fabrics for the textile industry </li></ul>
  69. 69. Halogen: Chlorine Applications: <ul><li>disinfectant: for swimming pools and water treatment plants </li></ul><ul><li>HCl is used for the removal of rust – known as pickling </li></ul>
  70. 70. Symbol: Halogen: Bromine <ul><li>Symbol: Br </li></ul><ul><li>Atomic number : 35 </li></ul><ul><li>Mass number: 80 </li></ul><ul><li>No. of protons = No. of electrons: 35 </li></ul><ul><li>No. of neutrons: 45 </li></ul><ul><li>Isotopes : Br-79 (50%), Br-81(50%) </li></ul><ul><li>Only non-metallic element which is liquid at room temperature </li></ul>
  71. 71. Preparation: Halogen: Bromine <ul><li>Bromine for commercial purposes is obtained by treating brines (from salt wells or seawater) with chlorine. </li></ul><ul><li>Cl 2 (g) + 2Br - (aq)  Br 2 (l) + 2Cl - (aq) </li></ul>
  72. 72. Applications: Halogen: Bromine <ul><li>C 2 H 4 Br 2 (1,2-dibromoethane) is used as an “anti-knock” in car petrol – makes the combustion of petrol more smoothly </li></ul><ul><li>CH 3 Br (methyl bromide) is used as a pesticide against parasitic worms </li></ul>
  73. 73. Applications: Halogen: Bromine <ul><li>Silver bromide is used in photographic film – coated on the surface of the photographic film </li></ul>
  74. 74. Halogen: Iodine <ul><li>Symbol: I </li></ul><ul><li>Mass number: 127 </li></ul><ul><li>No. of protons: 53 </li></ul><ul><li>No. of electrons: 53 </li></ul><ul><li>No. of neutrons: 74 </li></ul>
  75. 75. Halogen: Iodine Preparation: <ul><li>Commercially prepared from oil well brines and Chilean sodium nitrate deposits, where it occurs as NaIO 3 </li></ul><ul><li>2NaIO 3 + 5NaHSO 3  I 2 + 3NaHSO 4 + 2Na 2 SO 4 + H 2 O </li></ul>
  76. 76. Halogen: Iodine Applications: <ul><li>Essential for the human body for the formation of thyroxine , a hormone secreted by thyroid gland – lack of iodine in the diet will result in hypothyroidism </li></ul><ul><li>KI is a common additive to table salt. </li></ul>
  77. 77. Halogen: Iodine Applications: <ul><li>Used as an antiseptic and disinfectant for wounds. </li></ul><ul><li>Silver Iodide (AgI) is used in high-speed photographic films. </li></ul>
  78. 78. Halogen: Iodine Applications: <ul><li>Silver Iodide is used as cloud-seeding particle for rain-making - 1g of AgI can form as many as 1 million billion seed crystals, which acts as nuclei for raindrop formation </li></ul><ul><li>Radioactive iodine, 131 I is used for the treatment of hyperthyroidism and thyroid cancer </li></ul>

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