Noble Gases An Overview Contents 1 Properties 1 1.1 Noble gas ............................................... 1 1.1.1 History ............................................ 1 1.1.2 Physical and atomic properties ................................ 2 1.1.3 Chemical properties ...................................... 3 1.1.4 Occurrence and production .................................. 5 1.1.5 Applications .......................................... 6 1.1.6 Discharge color ........................................ 7 1.1.7 See also ............................................ 7 1.1.8 Notes ............................................. 7 1.1.9 References .......................................... 9 2 Elements 11 2.1 Helium ................................................. 11 2.1.1 History ............................................ 11 2.1.2 Characteristics ........................................ 13 2.1.3 Isotopes ............................................ 16 2.1.4 Compounds .......................................... 17 2.1.5 Occurrence and production .................................. 18 2.1.6 Applications .......................................... 19 2.1.7 Inhalation and safety ..................................... 20 2.1.8 Additional images ....................................... 21 2.1.9 See also ............................................ 21 2.1.10 References .......................................... 21 2.1.11 Bibliography ......................................... 26 2.1.12 External links ......................................... 26 2.2 Neon .................................................. 27 2.2.1 History ............................................ 27 2.2.2 Isotopes ............................................ 28 2.2.3 Characteristics ........................................ 29 2.2.4 Occurrence .......................................... 29 2.2.5 Applications .......................................... 29 2.2.6 Compounds .......................................... 30 i ii CONTENTS 2.2.7 See also ............................................ 30 2.2.8 References .......................................... 30 2.2.9 External links ......................................... 31 2.3 Argon ................................................. 31 2.3.1 Characteristics ........................................ 31 2.3.2 History ............................................ 32 2.3.3 Occurrence .......................................... 32 2.3.4 Isotopes ........................................... 32 2.3.5 Compounds .......................................... 33 2.3.6 Production .......................................... 33 2.3.7 Applications .......................................... 33 2.3.8 Safety ............................................. 36 2.3.9 See also ............................................ 36 2.3.10 References .......................................... 36 2.3.11 Further reading ........................................ 37 2.3.12 External links ......................................... 37 2.4 Krypton ................................................ 37 2.4.1 History ............................................ 38 2.4.2 Characteristics ........................................ 38 2.4.3 Applications .......................................... 39 2.4.4 Precautions .......................................... 40 2.4.5 See also ............................................ 40 2.4.6 References .......................................... 40 2.4.7 Further reading ........................................ 41 2.4.8 External links ......................................... 41 2.5 Xenon ................................................. 41 2.5.1 History ............................................ 41 2.5.2 Characteristics ........................................ 42 2.5.3 Occurrence and production .................................. 43 2.5.4 Isotopes and isotopic studies ................................. 43 2.5.5 Compounds .......................................... 44 2.5.6 Applications .......................................... 46 2.5.7 Precautions .......................................... 49 2.5.8 See also ............................................ 49 2.5.9 References .......................................... 49 2.5.10 External links ......................................... 56 2.6 Radon ................................................. 56 2.6.1 Characteristics ........................................ 57 2.6.2 History and etymology .................................... 59 2.6.3 Occurrence .......................................... 60 2.6.4 Applications .......................................... 62 CONTENTS iii 2.6.5 Health risks .......................................... 63 2.6.6 See also ............................................ 66 2.6.7 References .......................................... 66 2.6.8 External links ......................................... 70 2.7 Ununoctium .............................................. 71 2.7.1 History ............................................ 71 2.7.2 Naming ............................................ 72 2.7.3 Characteristics ........................................ 73 2.7.4 See also ............................................ 74 2.7.5 Notes ............................................. 74 2.7.6 References .......................................... 75 2.7.7 Further reading ........................................ 77 2.7.8 External links ......................................... 77 3 Text and image sources, contributors, and licenses 78 3.1 Text .................................................. 78 3.2 Images ................................................. 84 3.3 Content license ............................................ 88 Chapter 1 Properties 1.1 Noble gas toxemia, the lethal effect of high-pressure oxygen, and nitrogen narcosis, the distracting narcotic effect of the ni- trogen in air beyond this partial-pressure threshold. Af- The noble gases make a group of chemical elements with ter the risks caused by the flammability of hydrogen be- similar properties: under standard conditions, they are came apparent, it was replaced with helium in blimps and all odorless, colorless, monatomic gases with very low balloons. chemical reactivity. The six noble gases that occur nat- urally are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the radioactive radon (Rn). 1.1.1 History For the first six periods of the periodic table, the no- Noble gas is translated from the German noun Edelgas, ble gases are exactly the members of group 18 of the [3] periodic table. It is possible that due to relativistic effects, first used in 1898 by Hugo Erdmann to indicate their the group 14 element flerovium exhibits some noble- extremely low level of reactivity. The name makes an gas-like properties,[1] instead of the group 18 element analogy to the term "noble metals", which also have low ununoctium.[2] Noble gases are typically highly unreac- reactivity. The noble gases have also been referred to as tive except when under particular extreme conditions. inert gases, but this label is deprecated as many noble gas compounds are now known.[4] Rare gases is another term The inertness of noble gases makes them very suitable [5] in applications where reactions are not wanted. For ex- that was used, but this is also inaccurate because argon ample: argon is used in lightbulbs to prevent the hot tung- forms a fairly considerable part (0.94% by volume, 1.3% by mass) of the Earth’s atmosphere due to decay of ra- sten filament from oxidizing; also, helium is breathed by [6] deep-sea divers to prevent oxygen and nitrogen toxicity. dioactive potassium-40. The properties of the noble gases can be well explained by modern theories of atomic structure: their outer shell of valence electrons is considered to be “full”, giving them little tendency to participate in chemical reactions, and it has been possible to prepare only a few hundred noble gas compounds. The melting and boiling points for a given noble gas are close together, differing by less than 10 °C Helium was first detected in the Sun due to its characteristic (18 °F); that is, they are liquids over only a small temper- spectral lines. ature range. Neon, argon, krypton, and xenon are obtained from air in Pierre Janssen and Joseph Norman Lockyer discovered an air separation unit using the methods of liquefaction a new element on August 18, 1868 while looking at the of gases and fractional distillation. Helium is sourced chromosphere of the Sun, and named it helium after the from natural gas fields which have high concentrations Greek word for the Sun, ήλιος (ílios or helios).[7] No of helium in the natural gas, using cryogenic gas sep- chemical analysis was possible at the time, but helium aration techniques, and radon is usually isolated from was later found to be a noble gas. Before them, in 1784, the radioactive decay of dissolved radium, thorium, or the English chemist and physicist Henry Cavendish had uranium compounds (since those compounds give off discovered that air contains a small proportion of a sub- alpha particles), which are equivalent in mass to the nuclei stance less reactive than nitrogen.[8] A century later, in of a helium-4 atom. Noble gases have several important 1895, Lord Rayleigh discovered that samples of nitro- applications in industries such as lighting, welding, and gen from the air were of a different density than nitro- space exploration. A helium-oxygen breathing gas is of- gen resulting from chemical reactions. Along with Scot- ten used by deep-sea