Radon
Atomic Number: 86
Symbol: Rn
Atomic Weight: 222.0176
Discovery: Fredrich Ernst Dorn 1898 or 1900 (Germany), discovered the element and called it radium emanation. Ramsay and Gray isolated the element in 1908 and named it niton.
Electron Configuration: [Xe] 4f14 5d10 6s2 6p6
Word Origin: from radium. Radon was once called niton, from the Latin word nitens, which means 'shining'
Isotopes: At least 20 isotopes of radon are known. Radon-222 is called thoron and emanates naturally from thorium. Thoron is an alpha-emitter with a half-life of 54.5 sec. Radon-219 is called actinon and emanates from actinium. It is an alpha-emitter with a half-life of 3.92 sec.
Properties: Radon has a melting point of -71° C, boiling point of -61.8 °C, gas density of 9.73 g/l, specific gravity of the liquid state of 4.4 at -62°C, specific gravity of the solid state of 4, usually with a valence of 0 (it does form some compounds, however, such as radon fluoride). Radon is a colorless gas at normal temperatures. It is also the heaviest of the gases. When it is cooled below its freezing point it displays a brilliant phosphorescence. The phosphorescence is yellow as the temperature is lowered, becoming orange-red at the temperature of liquid air. Inhalation of radon presents a health risk. Radon build-up is a health consideration when working with radium, thorium, or actinium. It is also a potential issue in uranium mines.
Sources: It is estimated that each square mile of soil to a depth of 6 inches contains approximately 1 g of radium, which releases radon to the atmosphere. The average concentration of radon is about 1 sextillion parts of air. Radon naturally occurs in some spring waters.
Element Classification: Inert Gas
Density (g/cc): 4.4 (@ -62°C)
Melting Point (K): 202
Boiling Point (K): 211.4
Appearance: heavy radioactive gas
Specific Heat (@20°C J/g mol): 0.094
Evaporation Heat (kJ/mol): 18.1
First Ionizing Energy (kJ/mol): 1036.5
Lattice Structure: Face-Centered Cubic
References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952), CRC Handbook of Chemistry & Physics (18th Ed.)
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