Radon

Radon - Rn

CAS: 10043-92-2
Description: Colorless, odorless, tasteless, radioactive gas
Classification: Noble Gas
Date of Discovery: 1898
Discoverer: Fredrich Ernst Dorn
Name Origin: From radium

Atomic Number: 86
Number of Neutrons: 136
Atomic Mass: (222) amu
Melting Point: -71 °C
Boiling Point: -61.7 °C
Density (293 K): 9.73 g/cm³
liquid, 4.4 g/cm³ (-62 °C)
solid, 4 g/cm³
Atomic volume: 50.5 cm³/mol
Electrical resistivity:
Thermal conductivity: 0.0000364 W/cmK
Enthalpy of atomization:
Enthalpy of vaporization: 16.40 kJ/mol
Enthalpy of fusion: 2.890 kJ/mol
Specific heat capacity: 0.09 J/gK

Energy levels: 2-8-18-32-18-8
Electron configuration: [Xe]4f ¹⁴5d¹⁰6s²6p⁶
Crystal Structure: Cubic face centered
Atomic radius: 1.34 Å
Covalent radius:
Oxidation States: usually 0
Electronegativity, Pauling:
Electron affinity: not stable
First ionization energy: 10.748 eV
2nd ionization energy:
3rd ionization energy:
Polarizability: 5.3 10^-24cm³

Isotope	Natural Abundance	Atomic Mass	Half-life	Decay Mode	Spin
¹⁹⁸Rn	197.9988	0.5 s
^199mRn	0.3 s		(13/2+)
¹⁹⁹Rn	198.9983	0.62 s		3/2-
²⁰⁰Rn	199.9957	1.06 s	; EC	0+
²⁰¹Rn	200.9955	7.0 s	; EC	(3/2-)
²⁰²Rn	201.9932	9.9 s	; EC	0+
^203mRn	28 s		13/2+
²⁰³Rn	202.9948	45 s	; EC	0+
²⁰⁴Rn	203.9914	1.24 m	; EC	0+
²⁰⁵Rn	204.9917	2.8 m	; EC	(5/2-)
²⁰⁶Rn	205.9902	5.7 m	; EC	0+
²⁰⁷Rn	206.9907	9.3 m	⁺, EC; ;	5/2-
²⁰⁸Rn	207.98963	24.3 m	; EC	0+
²⁰⁹Rn	208.99038	29 m	⁺;	5/2-
²¹⁰Rn	209.98968	2.4 h	; EC	0+
²¹¹Rn	210.99059	14.6 h	⁺;	1/2-
²¹²Rn	211.990689	24 m		0+
²¹³Rn	212.99387	25.0 ms		9/2+
²¹⁴Rn	213.99535	0.27 µs		0+
²¹⁵Rn	214.99873	2.3 µs		(9/2+)
²¹⁶Rn	216.00026	45 µs
²¹⁷Rn	217.003915	0.6 ms		9/2+
²¹⁸Rn	218.005586	35 ms		0+
²¹⁹Rn	219.009475	3.96 s		(5/2+)
²²⁰Rn	220.011384	55.6 s		0+
²²¹Rn	221.0156	25 m	; ^-	7/2+
²²²Rn	222.017570	3.8235 d		0+
²²³Rn	23 m	^-
²²⁴Rn	1.8 h	^-	0+
²²⁵Rn	4.5 m	^-	7/2
²²⁶Rn	7.4 m	^-
²²⁷Rn	2 s	^-
²²⁸Rn	65 s	^-
The element was discovered in 1900 by Dorn, who called it radium emanation. In 1908 Ramsay and Gray, who named it niton (L. nitens, "shining"), isolated the element and determined its density, finding it to be the heaviest known gas. It is essentially inert and occupies the last place in the zero group of gases in the Periodic Table. Since 1923, it has been called radon. Thirty-nine isotopes and isomers are known. Radon-222, coming from radium, has a half-life of 3.823 days and is an alpha emitter; Radon-220, emanating naturally from thorium and called thoron, has a half-life of 55.6 seconds and is also an alpha emitter. Radon-219 emanates from actinium and is called actinon. It has a half-life of 3.96 second and is also on alpha emitter. It is estimated that every square mile of soil to a depth of 6 inch contains about 1 g of radium, which releases radon in tiny amounts to the atmosphere. Radon is present in some spring waters, such as those at Hot Springs, Arkansas. On the average, one part of radon is present to 1 x 10²¹ part of air. At ordinary temperatures radon is a colorless gas; when cooled below the freezing point, radon exhibits a brilliant phosphorescence which becomes yellow as the temperature is lowered and orange-red at the temperature of liquid air. It has been reported that fluorine reacts with radon, forming radon fluoride. Radon clathrates have also been reported. Radon is still produced for therapeutic use by a few hospitals by pumping it from a radium source and sealing it in minute tubes, called seeds or needles, for application to patients. This practice has now been largely discontinued as hospitals can order the seeds directly from suppliers, who make up the seeds with the desired activity for the day of use. Care must be taken in handling radon, as with other radioactive materials. The main hazard is from inhalation of the element and its solid daughters, which are collected on dust in the air. Good ventilation should be provided where radium, thorium, or actinium is stored to prevent build-up of this element. Radon build-up is a health consideration in uranium mines. Recently radon build-up in homes has been a concern. Many deaths from lung cancer are caused by radon exposure. In the U.S. it is recommended that remedial action be taken if the air in homes exceeds 4 pCi/l. LINKS: Common Indoor Air Pollutants: Radon Radon in Earth, Air, and Water Radon Facts Radon Links Return Sources for the information on this website include: Lide, David R., ed. CRC Handbook of Chemistry and Physics, 78th Ed., 1997-1998.

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