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Comprehensive Overview of Noble Gases: Properties, Reactions, and Applications

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This document provides an in-depth exploration of noble gases, particularly focusing on their discovery, properties, and various applications. It discusses the contributions of notable scientists like Henry Cavendish, Janssen, Lockyer, and Lord Raleigh, notably the non-reactivity of Helium, the characteristics of Xenon fluorides, and their applications in superconductors and diving tanks. The chemistry of these gases, including potential compounds and reactions, is analyzed, along with insights into isotopes and their industrial uses. A thorough understanding of these elements' behavior and utility is essential for advancements in both chemistry and technology.

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Comprehensive Overview of Noble Gases: Properties, Reactions, and Applications

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  1. Ch 18. Group 18

  2. Elements 1785 Henry Cavendish air contains < 1% of gas that does not react with O2 under electric discharge 1868 (Aug 18) Janssen / Lockyer solar eclipse, yellow line in solar spectrum (He) 1895 Lord Raleigh N2 in air is denser than N2 from ammonia (due to Ar in air sample) Commercial sources: no naturally occurring compounds He – impurity in natural gas (from radioactive decay underground) Ar to Xe – distillation of liquid air Rn – none, intensely radioactive (t1/2 ~ 4 days)

  3. Applications He coolant (bp = 4.2K, lowest known); esp. for superconductors (MRI/NMR) balloons, etc. lifting power = 1 kg / m3 diving air tanks, He has a lower blood solubility than N2 Other gases inert atmosphere (ex – welding) lighting (electric discharge to get excited state)

  4. Noble gas chemistry I / eV He 24.6 Ne 21.6 Ar 15.8 Kr 14.0 Xe 12.1 Rn 10.7

  5. Compounds Consider MO theory – bonding depends on symmetry and orbital energies, trends throughout the p-block Xe (g) + F2 (g)  XeF2 (use excess Xe) Xe + 2 F2  XeF4 (D4h) Xe + 3 F2  XeF6 (use excess F2) XeF2 colorless sublimable solid linear molecular structure, isoelectronic w IF2-, Xe-F b.l. ~ 200 pm 400 C or uv

  6. XeF2, XeF4, and XeF6 XeF6 or (XeF5+F-)n XeF4 crystals

  7. XeFn reactions XeF2 + SbF5 XeF+SbF6 (s) + HN(SO2F)2 XeF+N(SO2F)2 (s) + HF + HSO3F  XeF+SO3F (s) XeF6 + SbF5 XeF5+SbF6 (s) XeF6 + 2 MF  M2XeF8 square anti-prism (Xe-F)+ isoelectronic w IF, Xe-F b.l. ~ 195 pm

  8. XeF+N(SO2F)2- XeF+SO3F- XeF+ and XeF5+ XeF5+RuF6- (s) < FeqXeFeq = 87° < FaxXeFeq = 78°

  9. Xenon oxides XeF2 + H2O  Xe + 2 HF + ½ O2 XeF6 + H2O  XeO3 (aq) + 6 HF (metathesis instead of hydrolysis is possible under controlled conditions) XeO3 + OH HXeO4  disproportionates in base XeO64 + Xe XeO3 is endoergic, and explosive (perxenate)

  10. Xenon oxyfluorides also: XeO2F2 , XeOF4, etc

  11. Xe(g) AuF3 [AuXe4](Sb2F11)2 SbF5/HF (superacid) Other compounds

  12. h Kr + F2 KrF2(s) unstable at RT, Hf ~ + 20 kJ/mol KrF2 + SbF5 (KrF)+ SbF6- a few other LA complexes are known -78°C Krypton chemistry

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