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Lecture 21 - Chapter 14 The Main ­Group Elements: ...

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Unformatted text preview: Chapter 14 The Main ­Group Elements: Applying Principles of Bonding and Structure The Main ­Group Elements: Applying Principles of Bonding and Structure 14.1 Hydrogen, the Simplest Atom 14.2 Group 1A(1): The Alkali Metals 14.3 Group 2A(2): The Alkaline Earth Metals 14.4 Group 3A(13): The Boron Family 14.5 Group 4A(14): The Carbon Family 14.6 Group 5A(15): The Nitrogen Family 14.7 Group 6A(16): The Oxygen Family 14.8 Group 7A(17): The Halogens 14.9 Group 8A(18): The Noble Gases Flame Colors Na K ProducTon and Use Electrolysis: 2 NaCl(l) → 2 Na(l) + Cl2(g) Sodium as a reducing agent: KCl(l) + Na(l) → 2 NaCl(l) + K(g) TiCl4 + 4 Na → Ti + 4 NaCl Group I Compounds •  Halides –  NaCl 50 million tons/year in U.S. –  PreservaTve, used on roads, water so]ener regeneraTon, feed stock for other chemicals –  KCl from natural brines. –  Plant ferTlizers, feed stock. Sodium Compounds Solvay Process ApplicaTons: Glass making, water treatment, paper making, common alkali Sodium Sulfate H2SO4(conc. aq) + NaCl(s) → NaHSO4(s) + HCl(g) NaHSO4(s) + NaCl(s) → Na2SO4(s) + HCl(g) In the Kra7 Process for making paper: Na2SO4(s) + 4 C(s) → Na2S(s) + 4 CO(g) 100 lb/ton paper Oxides and Hydroxides •  ReacTon with oxygen produces several ionic oxides. –  In limited oxygen supplies: •  M2O (small amounts of Li2O2 from Li). –  In excess oxygen: •  Li and Na form the peroxide, M2O2. •  K, Rb and Cs form the superoxide MO2. Carbonates •  Li2CO3 is unstable relaTve to the oxide. –  Used to treat manic depression (1 ­2 g /day). •  Na2CO3 primarily used to manufacture glass. –  Currently mined from rich U.S. resources but can be manufactured by the Solvay process. Detergents and Soaps Uses of Alkali Metals •  Lithium –  Alloys of Li ­Al ­Mg for aircra] and space applicaTons. –  Bacery anodes. •  Sodium –  Heat ­transfer medium in nuclear reactors. –  Sodium vapor lamps. Group 2: The Alkaline Earth Metals Emerald is based on the mineral beryl: 3BeO Al2O3 6SiO2 Group 2 •  Principle forms: –  carbonates, sulfates and silicates •  Oxides and hydroxides only sparingly soluble. –  Basic or “alkaline” •  Compounds do not decompose on heaTng. –  Therefore named “earths” •  Heavier elements compounds are more reacTve and are similar to Group I (also in other respects). Table 22.4 Some ProperTes of the Group 2 (Alkaline Earth) Metals Three diagonal relaTonships in the periodic table. Lagce energies of the Group 1A(1) and 2A(2) chlorides. Standing in Group 2A(2), looking backward to Group 1A(1) and forward to 3A(13). Beryllium •  UnreacTve toward air and water. •  BeO does not react with water. •  Be and BeO dissolve in strongly basic soluTons to form the BeO22 ­ ion (therefore are acidic). •  BeCl2 and BeF2 melts are poor conductors: –  Therefore they are covalent rather than ionic solids. Beryllium Chloride The dimeric structure of gaseous aluminum chloride. Figure 14.5 Phase diagram of carbon. Figure 14.6 Buckyballs and nanotubes. Crystals of buckminsterfullerene (C60) Nanotubes Figure 14.7 Three of the several million known organic compounds of carbon. Figure 14.8 Structures of the silicate anions in some minerals. ...
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