1. 1 Chapter Nonmetallic Elements and Their Compounds Dr.Monther F.Salem

2. 2 General Properties of Nonmetals Properties of nonmetals - more varied than those of metals Physical state –Gases: hydrogen, oxygen, nitrogen, fluorine, chlorine, and the noble gases –Liquid : bromine –Solids: All the remaining nonmetals Poor conductors of heat and electricity Exhibit either positive or negative oxidation numbers. Dr.Monther F.Salem

3. 3 Metalloids - small group of elements have properties characteristic of both metals and nonmetals. More electronegative than metals Electronegativity increases from left to right across any period and from bottom to top in any group in the periodic table With the exception of hydrogen, the nonmetals are concentrated in the upper right-hand corner of the periodic table Compounds formed by a combination of metals with nonmetals tend to be ionic, having a metallic cation and a nonmetallic anion. Dr.Monther F.Salem

4. 4 Nonmetals and Metalloids on the Periodic Table Nonmetals coded in blue and metalloids in orange.. Dr.Monther F.Salem

5. 5 Hydrogen Simplest known element Exists as a diatomic molecule H 2 is a colorless, odorless, and nonpoisonous gas. At 1 atm, boiling point is −252.9°C (20.3 K). Most abundant element in the universe Dr.Monther F.Salem

6. 6 Ground-state electron configuration: 1s 1. –Resembles the alkali metals (Group 1A) in that it can be oxidized to the H + ion, which exists in aqueous solutions in the hydrated form. –Resembles the halogens (Group 7A) in that it forms the hydride H − (hydride ion) - isoelectronic with helium (1s 2 ) Found in a large number of covalent compounds. Unique capacity to form hydrogen bonds Dr.Monther F.Salem

7. 7 Preparation –Industrial scale –Laboratory scale Dr.Monther F.Salem

8. 8 Laboratory Generation of Hydrogen Dr.Monther F.Salem

9. Hydrides Binary compounds of hydrogen –has an intermediate electronegativity ionic hydrides –LiH covalent hydrides –HF metallic hydrides –NiH 2

10. Ionic Hydrides white solids metal cation and hydride ion very reactive LiH(s) + H 2 O(l)  LiOH(aq) + H 2 (g) reducing agents CaH 2 (s) + H 2 O(l)  Ca(OH) 2 (s) + H 2 (g)

11. Covalent Hydrides covalently bonds with all nonmetals and weakly electropositive metals gases at room temperature –hydrogen can be: nearly neutral substantially positive slightly negative

12. Neutral Covalent Hydrides low polarity –only dispersion forces Examples: –PH 3 –CH 4 –Hexene CH 4 (g) + 2O 2 (g)  CO 2 (g) + 2H 2 O(g)

13. Positive Covalent Hydrides high melting and boiling points –protonic bridging Examples: –ammonia –water –hydrogen fluoride

14. Negative Covalent Hydrides Contains hydridic hydrogens Very reactive towards oxygen Examples: –B 2 H 6 –SiH 4 –GeH 4 GeH 4 (g) + 2O 2 (g)  GeO 2 (s) + 2H 2 O(l)

15. 15 Binary hydrides - compounds containing hydrogen and another element, either a metal or a nonmetal. Types of hydrides –Ionic hydrides direct combination of molecular hydrogen and any alkali or alkaline earth metal –Solids with high melting points –Contain the strong Br Ø nsted base, H − Dr.Monther F.Salem

16. 16 –covalent hydrides - the hydrogen atom is covalently bonded to the atom of another element Types of covalent hydrides –Discrete unit structure – NH 3 –Polymeric structure – (BeH 2 ) x –Interstitial hydrides – compounds of hydrogen and transition metal in which the atomic ratio is not constant – titanium hydride ranges from TiH 1.8 to TiH 2. Dr.Monther F.Salem

17. 17 Binary Hydrides of Representative Elements Dr.Monther F.Salem

18. 18 Isotopes of hydrogen –Hydrogen has three naturally occurring isotopes –, hydrogen, (99.985%) –, deuterium, symbol D, (0.015%) –, tritium, symbol T, (radioactive, t 1/2 =12.5 years. Dr.Monther F.Salem

19. Isotopes of Hydrogen Three common isotopes: –Protium (H) common hydrogen 99.985% abundant –Deuterium (D) one neutron 0.015% abundant –Tritium (T) two neutrons 1x10 -15 % abundant

20. 20Dr.Monther F.Salem Deuterium containing water, D 2 O Called heavy water or deuterated water Toxic Affects reaction rates – isotopic effect

21. 21 Hydrogenation - addition of hydrogen to compounds containing multiple bonds, usually carbon to carbon double or triple bonds. –Catalyzed by metals (Pt or Cd) –Important in food industry Dr.Monther F.Salem

22. 22 Hydrogen Economy –Hydrogen an alternative fuel source to petroleum fuels For automobiles Electrical power generation –Pollution free fuel –Present dilemma – how to obtain sufficient amounts of H 2 –Splitting water using solar energy – one possible source for the needed H 2. Dr.Monther F.Salem

23. Reactions of Hydrogen with Diatomics 2H 2 (g) + O 2 (g)  2H 2 O(g) (very fast) H 2 (g) + F 2 (g)  2HF(g) (very fast) 3H 2 (g) + N 2 (g)  2NH 3 (g) (very slow)

24. Reduction Reactions of Hydrogen Acts to reduce many metallic elements CuO(s) + H 2 (g)  Cu(s) + H 2 O(g) Can also reduce double and triple bonds with a catalyst H 2 C=CH 2 (g) + H 2 (g)  H 3 C—CH 3 (g)

25. 25 Carbon 0.09 % by mass of Earth’s crust An essential element of living matter A component of natural gas, petroleum and coal. Combines with oxygen to form carbon dioxide in the atmosphere Occur as carbonates in limestone and chalk. Found free in allotropic forms of diamond and graphite Dr.Monther F.Salem

26. 26 Phase Diagram for Allotropic Forms of Carbon Dr.Monther F.Salem

27. 27 catenation – carbon has the unique ability to form long chains stable rings –Responsible for the millions of carbon- containing compounds Reacts with –Metals to form carbides (strong bases), CaC 2 –Silicon to form carborundum, SiC –Nitrogen to form cyanides, Toxic Readily complexes metals Dr.Monther F.Salem

28. 28 Cyanide Pond for Extracting Gold Dr.Monther F.Salem

29. 29 Important oxides –Carbon monoxide (CO) Formed during incomplete combustion Colorless, odorless gas Used in metallurgical processes Used in organic synthesis Not acidic Only slightly soluble in water Burns to produce carbon dioxide Dr.Monther F.Salem

30. 30 –Carbon dioxide (CO 2 ) Colorless and odorless gas Nontoxic—although it is a simple asphyxiant Acidic oxide – forms carbonic acid Uses –“ carbonated” beverages –Fire extinguishers –Manufacture of baking soda (NaHCO 3 ) –Manufacture of soda ash (Na 2 CO 3 ) –“Dry ice” as a refrigerant Dr.Monther F.Salem

31. 31 Nitrogen and Phosphorous Nitrogen –Mineral sources of nitrogen: saltpeter (KNO 3 ) and Chile saltpeter (NaNO 3 ) –Nitrogen is an essential element of life A component of proteins and nucleic acids –N 2 is obtained by the fractional distillation of air –N 2 contains a triple bond and is stable –Forms variable oxidation states Dr.Monther F.Salem

32. 32Dr.Monther F.Salem

33. 33 Common (important) forms of nitrogen –Nitride ion, N 3−, a strong Br Ø nsted base –Ammonia, NH 3 Undergoes autoionization to produce the highly basic amide ion, NH 2 - –Hydrazine, N 2 H 4 Basic Reducing Agent Dr.Monther F.Salem

34. 34 Important oxides –Nitrous oxide (N 2 O) Supports combustion Used as dental anesthetic –Nitric oxide (NO) Produced in atmosphere (form of nitrogen fixation) Colorless gas Produced in auto exhaust Paramagnetic Resonance stabilized Dr.Monther F.Salem

35. 35 –Nitrogen Dioxide (NO 2 ) Toxic Paramagnetic Dimerizes to N 2 O 4 in the liquid and gas phases Acidic oxide –Shown in a disproportionation reaction with cold water Dr.Monther F.Salem

36. 36 Nitric acid (HNO 3 ) –Powerful oxidizing agent –Can be reduced to NH 4 + –Aqua regia – 1:3 mixture of concentrated HCl and concentrated HNO 3 Even oxidizes gold –Oxidizes nonmetals to oxoacids Dr.Monther F.Salem

37. The production of NO 2 gas when copper reacts with concentrated nitric acid. 37 Used in manufacture of Fertilizers Drugs Explosives Dyes Dr.Monther F.Salem

38. 38 Phosphorus –Occurs most commonly in nature as phosphate rocks calcium phosphate [Ca 3 (PO 4 ) 2 ] fluoroapatite [Ca 5 (PO 4 ) 3 F] –Elemental phosphorus produced by –Allotropic forms of phosphorus Red phosphorus White phosphorus Ca 5 (PO 4 ) 3 F Dr.Monther F.Salem

39. 39 Allotropes of Phosphorus Dr.Monther F.Salem

40. 40 –Reactions of phosphorus Formation of phosphine (PH 3 ) Formation of phosphoric acid Reaction with the halogens Dr.Monther F.Salem

41. 41 Acid production from halides Reaction with oxygen to produce acidic oxides Dr.Monther F.Salem

42. 42 Structure of P 4 O 6 and P 4 O 10 Dr.Monther F.Salem

43. 43 Oxoacids of phosphorus Dr.Monther F.Salem

44. 44 Oxygen and Sulfur Oxygen –Most abundant element in Earth’s crust (46% by mass) –Atmosphere contains about 21% by volume (23% by mass) –Diatomic molecule (O 2 ) in the free state –Essential for human life –Alloptropic forms: O 2 and O 3 (ozone) –Strong oxidizing and bleaching agent

45. Dr.Monther F.Salem45 –Oxides Types of oxides –Normal oxide, O 2 2− –Peroxide, O 2 2− –Superoxide, O 2 − All are strong Br Ø nsted bases

46. Dr.Monther F.Salem46 Bonding in oxides – ionic to covalent left to right on the periodic table Acid-base character of oxides – –Basicity increases down a group –Peroxides H 2 O 2 (hydrogen peroxide) – most common example Basic Amphoteric Acidic

47. Dr.Monther F.Salem47 Structure of H 2 O 2

48. Dr.Monther F.Salem48 Polar Miscible with water Decomposes spontaneously Used as mild antiseptic (3% solution) or bleach agent (higher concentrations) Used as rocket fuel due to high heat of decompostion Serves as an oxidzing agent Serves as a reducing agent

49. Dr.Monther F.Salem49 –Ozone Toxic, light-blue gas Pungent odor Essential component of the atmosphere Structure Powerful oxidizing agent Preparation

50. Dr.Monther F.Salem50 Preparation of O 3

51. Dr.Monther F.Salem51 Sulfur –Constitutes about 0.06 % of Earth’s crust by mass –Occurs commonly in nature in the elemental form Sedimentary deposits Gypsum (CaSO 4. 2H 2 O) and various sulfide minerals such as pyrite (FeS 2 ) –Most common allotropic forms Monoclinic Rhombic – most stable form – S 8 FeS 2

52. Dr.Monther F.Salem52 Puckered Ring of S 8

53. Dr.Monther F.Salem53 –The Frasch process. Three concentric pipes are inserted into a hole drilled down to the sulfur deposit. Superheated water is forced down the outer pipe into the sulfur, causing it to melt. Molten sulfur is then forced up the middle pipe by compressed air.

54. Dr.Monther F.Salem54 –Forms wide variety of oxidation numbers

55. Dr.Monther F.Salem55 –Hydrogen sulfide – H 2 S Used in qualitative analysis Preparation Colorless gas with odor of rotten eggs Toxic Weak diprotic acid Reducing agent in basic solution

56. Dr.Monther F.Salem56 –Oxides of sulfur Sulfur dioxide (SO 2 ) –Pungent colorless gas –Toxic –Preparation –Acidic oxide –Oxidation

57. Dr.Monther F.Salem57 Sulfur trioxide (SO 3 ) –Involved in acid rain –Used in the production of sulfuric acid (H 2 SO 4 ) in the contact process* *Vanadium(V) oxide (V 2 O 5 ) is the catalyst used for the key second step.

58. Dr.Monther F.Salem58 Sulfuric acid –Diprotic acid –Colorless, viscous liquid (m.p. 10.4°C) –Concentrated sulfuric acid is 98 % H 2 SO 4 by mass (density 1.84 g/cm3), 18 M. –Oxidizing strength of sulfuric acid depends on temperature and concentration. –Cold dilute sulfuric acid reacts with active metals

59. Dr.Monther F.Salem59 –Hot concetrated sulfuric acid reacts with less active metals –Depending on the reducing agent, sulfate may be reduced –Oxidizes nonmetals

60. Dr.Monther F.Salem60 Carbon disulfide (CS 2 ) –Colorless, flammable liquid (b.p. 46°C) –Preparation –SIightly soluble in water –Solvent for nonpolar substances Sulfur hexafluoride (SF 6 ) –Preparation –Colorless, nontoxic, inert gas

61. Dr.Monther F.Salem61 The Halogens The halogens—fluorine, chlorine, bromine, and iodine—are reactive nonmetals.

62. Dr.Monther F.Salem62 All are highly reactive and toxic Magnitude of reactivity and toxicity generally decreases from fluorine to iodine. The chemistry of fluorine differs from that of the rest of the halogens in the following ways: –Fluorine is the most reactive due to the relative weakness of the F−F bond. –The difference in reactivity between fluorine and chlorine is greater than that between chlorine and bromine.

63. Dr.Monther F.Salem63 –Hydrogen fluoride (HF) has a relatively high boiling point (19.5°C) –Hydrofluoric acid is a weak acid, all other hydrohalic acids are strong acids. –Fluorine uniquely reacts with cold sodium hydroxide solution to produce oxygen difluoride as follows: –Silver fluoride (AgF) is soluble. All other silver halides (AgCl, AgBr, and AgI) are insoluble.

64. Dr.Monther F.Salem64 Elemental state, halogens form diatomic molecules (X 2 ). In nature, always found combined with other elements. –Chlorine, bromine, and iodine occur as halides in seawater –Fluorine occurs in the minerals fluorite (CaF 2 ) and cryolite (Na 3 AlF 6 ). All isotopes of astatine (As) are radioactive

65. Dr.Monther F.Salem65 Preparation and Properties of F 2 and Cl 2 – determined by their strong oxidizing capability –Fluorine From liquid HF At 70 o C

66. Dr.Monther F.Salem66 Electrolytic Preparation of F 2 Note that because H 2 and F 2 form an explosive mixture, these gases must be separated from each other.

67. Dr.Monther F.Salem67 –Chlorine Electrolysis of molten NaCl Overall reaction Chlor-alkali process –Designed to prevent side reactions –Mercury cell –Diaphragm cell

68. Dr.Monther F.Salem68 Mercury Cell in the Chlor-alkali Process

69. Dr.Monther F.Salem69 Diaphragm Cell in the Chlor-alkali Process

70. Dr.Monther F.Salem70 Compounds of the Halogens –Either ionic or covalent. The fluorides and chlorides especially those belonging to the alkali metal and alkaline earth metal are ionic compounds (except halides of Be). Most of the halides of nonmetals are covalent compounds. –Oxidation numbers range from −1 to +7 except F which can only be 0 (in F 2 ) and −1, in all compounds.

71. Dr.Monther F.Salem71 –Hydrogen Halides Preparation from elements – can occur violently Preparation varies with the halogen, for example HCl HBr HF

72. Dr.Monther F.Salem72 –Industrial uses of hydrogen fluoride (HF) Reactive enough to etch glass Used in the manufacture of Freons –Industrial uses of hydrogen chloride (HCl) Preparation of hydrochloric acid Inorganic chlorides Various metallurgical processes

73. Dr.Monther F.Salem73 –Aqueous solutions of HX Acidic Variation in acid strength –Oxoacids – halogens form a series of acids Only Cl forms the entire series increasing acid strength

74. Dr.Monther F.Salem74

75. Dr.Monther F.Salem75 Uses of the halogens –Fluorine UF 6 separating isotopes of U Production of poly tetrafluorethyline (Teflon ©) –Chlorine Biological role as Cl − (aq) Industrial bleaching – Cl 2 Water purification – Cl 2, ClO − Organic solvents – CHCl 3 Polymer production - PVC

76. Dr.Monther F.Salem76 –Bromine Insecticides (BrCH 2 CH 2 Br) Scavenger for Pb in gasoline Photographic films (AgBr) –Iodine Antiseptic (tincture of iodine) Thyroxine (thyroid hormone derivative) Cloud seeding (AgI)

77. THE NOBLE GASES

78. The elements in group 0, on the right of the periodic table, are called the noble gases. He Rn Xe Kr Ar Ne helium neon argon krypton xenon radon

79. Electron Structure and Reactivity fully occupied outer shells. All the elements in this group have fully occupied outer shells. least chemically reactive elements. They are the least chemically reactive elements. The stable arrangement means that the noble gases do not form chemical bonds with each other or other elements. monatomic They are monatomic which means they exist as individual atoms. Ar Ne He 2 2,8 2,8,8

80. Uses of Noble Gases You might think that a group of elements that have almost no reactions would have few uses. You would be wrong! They have many uses, mostly based upon their ability to prevent other (undesirable) reactions taking place.

81. Uses of Helium -Balloons (big and small). -Protective gas for growing silicon crystals in silicon chip manufacture. - -Rare documents preservation (i.e. US Declaration of Independence). - -Pressurizing agent for liquid fuel rockets (inert so won't react). -Coolant for the super-conductors used in body scanners.

82. Uses of Neon -Fluorescent lights and ‘neon’ signs. -TV tubes. -Neon lasers.

83. Uses of Argon -Used to fill light bulbs because the filament will not react with argon. -Used as an inert gas shield for arc welding and cutting especially metals easily damaged by oxygen such as aluminium & stainless steel. -Argon is involved in dating the ages of rocks by potassium-argon dating.

84. Patterns: Density! -There can be few chemical patterns for a group as unreactive as this. -There are still trends in physical properties

85. -There are also trends in boiling point. -Can you predict the B.Pts of Kr Xe and Rn?