Radon Chemische Eigenschaften,Einsatz,Produktion Methoden
ERSCHEINUNGSBILD
FARBLOSES GAS.
ARBEITSPLATZGRENZWERTE
TLV nicht festgelegt (ACGIH 2005).
MAK nicht festgelegt (DFG 2005).
AUFNAHMEWEGE
Aufnahme in den Körper durch Inhalation.
WIRKUNGEN NACH WIEDERHOLTER ODER LANGZEITEXPOSITION
Krebserzeugend für den Menschen. (S. Anm.)
LECKAGE
Belüftung. Persönliche Schutzausrüstung: Umgebungsluftunabhängiges Atemschutzgerät.
Beschreibung
Radon, Rn, is a gaseous radioactive element from the noble gases in family eight on the periodic table. There are 18 radioactive isotopes of radon, all of which have short half-lives. For example, radon 222 has a half-life of 3.8 days. Radon is a colorless gas that is soluble in water. It can be condensed to a colorless transparent liquid and to an opaque, glowing solid. Radon is the heaviest gas known, with a density of 9.72 g/L at 32°F.
Chemische Eigenschaften
colourless gas
Physikalische Eigenschaften
Radon gas fits the criteria to be classed as a noble element located in group 18(VIIIA) orgroup 0. It is the only noble “inert” gas that is naturally radioactive. It is the heaviest of thegases in group 18.
Radon gas is easily converted to a liquid and will become solid at the relatively hightemperature of –71°C. As a solid, it glows with a yellow light. Its melting point is –71°C, itsboiling point is –62°C, and its density is 0.00973g/cm
3.
Isotopes
There are 37 isotopes of radon. All are radioactive. None are stable. They rangein mass numbers from Rn-196 to Rn-228. Their half-lives range from a few microsecondsto 3.8235 days for Rn-222, which is the most common. It is a gas that is the resultof alpha decay of radium, thorium, or uranium ores and underground rocks.
Origin of Name
Originally named “niton” after the Latin word for “shining,” it was
given the name “radon” in 1923 because it is the radioactive decay gas of the element
radium.
Occurrence
Radon’s source is a step in the transmutation of several elements: uranium → thorium →radium → radon → polonium → lead. (There are a number of intermediate decay productsand steps involved in this process.) Radon-222 forms and collects just a few inches below thesurface of the ground and is often found in trapped pockets of air. It escapes through poroussoils and crevices.
Charakteristisch
Radon is the heaviest of the noble gases and is the only one that is radioactive. It is thedecay product of radium, thorium, and uranium ores and rocks found underground. As itdecays, it emits alpha particles (helium nuclei) and is then transmuted to polonium andfinally lead. The Earth’s atmosphere is just 0.0000000000000000001% radon, but becauseradon is 7.5 times heavier than air, it can collect in basements and low places in buildingsand homes.
Verwenden
Radon’s main use is as a short-lived source of radioactivity for medical purposes. It iscollected from the decay of radium as a gas and sealed in small glass capsules that are theninserted at the site of the cancer. It is also used to trace leaks in gas and liquid pipelines and tomeasure their rate of flow. The rate at which radon gas escapes from the Earth is one measurementthat helps scientists predict earthquakes.
Definition
A colorless monatomic radioactive element of the rare-gas group, now known to form unstable compounds. It has 19 short-lived radioisotopes; the most stable, radon-222, is a decay product of radium-226 and itself disintegrates into an isotope of polonium with a half-life of 3.82 days.
222Rn is sometimes used in radiotherapy. Radon occurs in uranium mines and is also detectable in houses built in certain areas of the country. Symbol: Rn; m.p. –71°C; b.p. –61.8°C; d. 9.73 kg m
–3 (0°C); p.n. 86.
Hazard
As for radium.
Sicherheitsprofil
A carcinogen. A common air contaminant. Radon is a noble gas and thus is relatively unreactive. Radiation Hazard: Natural isotope *zORn (Thoron, Thorium Series), T1/2 = 55 seconds, decays to radoactive 2'6Po by alphas of 6.3 MeV. Natural isotope 222Rn (Uranium Series), T1/2 = 3.8 days, decays to radioactive permissible levels are gven for 222Rn in equilibrium with its daughters. The chief hazard from this isotope is inhalation of the gaseous element and its solid daughters, whch are collected on the normal dust of the air. Ths material is deposited in the lungs and has been considered to be a major causative agent in the hgh incidence of lung cancer found in uranium miners. Radon and its daughters bdd up to an equhbrium value in about a month from radum compounds, whde the bdd-up from uranium compounds is negligble. Good ventilation of areas where radium is handled or stored is recommended to prevent accumulation of hazardous concentration of Rn and its daughters. Accumulation of radon in homes has been implicated in increased incidence of lung cancers. This accumulation is found in wellinsulated buildtngs located over land that has concentrations of uranium
Carcinogenicity
Radon and its isotopic forms radon-222 and radon-220 are known to be human carcinogens based on sufficient evidence of carcinogenicity from studies in humans.
Radon Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
