Radon

  • radon, 86rn
    radon
    pronunciationn/ (ray-don)
    appearancecolorless gas
    mass number[222]
    radon in the periodic table
    hydrogen helium
    lithium beryllium boron carbon nitrogen oxygen fluorine neon
    sodium magnesium aluminium silicon phosphorus sulfur chlorine argon
    potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton
    rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon
    caesium barium lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury (element) thallium lead bismuth polonium astatine radon
    francium radium actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium nihonium flerovium moscovium livermorium tennessine oganesson
    xe

    rn

    og
    astatineradonfrancium
    atomic number (z)86
    groupgroup 18 (noble gases)
    periodperiod 6
    blockp-block
    element category  noble gas
    electron configuration[xe] 4f14 5d10 6s2 6p6
    electrons per shell2, 8, 18, 32, 18, 8
    physical properties
    phase at stpgas
    melting point202 k ​(−71 °c, ​−96 °f)
    boiling point211.5 k ​(−61.7 °c, ​−79.1 °f)
    density (at stp)9.73 g/l
    when liquid (at b.p.)4.4 g/cm3
    critical point377 k, 6.28 mpa[1]
    heat of fusion3.247 kj/mol
    heat of vaporization18.10 kj/mol
    molar heat capacity5r/2 = 20.786 j/(mol·k)
    vapor pressure
    p (pa) 1 10 100 1 k 10 k 100 k
    at t (k) 110 121 134 152 176 211
    atomic properties
    oxidation states0, +2, +6
    electronegativitypauling scale: 2.2
    ionization energies
    • 1st: 1037 kj/mol
    covalent radius150 pm
    van der waals radius220 pm
    color lines in a spectral range
    spectral lines of radon
    other properties
    natural occurrencefrom decay
    crystal structureface-centered cubic (fcc)
    face-centered cubic crystal structure for radon
    thermal conductivity3.61×103  w/(m·k)
    magnetic orderingnon-magnetic
    cas number10043-92-2
    history
    discoveryernest rutherford and robert b. owens (1899)
    first isolationwilliam ramsay and robert whytlaw-gray (1910)
    main isotopes of radon
    iso­tope abun­dance half-life (t1/2) decay mode pro­duct
    210rn syn 2.4 h α 206po
    211rn syn 14.6 h ε 211at
    α 207po
    222rn trace 3.8235 d α 218po
    224rn syn 1.8 h β 224fr
    category category: radon
    | references

    radon is a chemical element with the symbol rn and atomic number 86. it is a radioactive, colorless, odorless, tasteless noble gas. it occurs naturally in minute quantities as an intermediate step in the normal radioactive decay chains through which thorium and uranium slowly decay into lead and various other short-lived radioactive elements; radon itself is the immediate decay product of radium. its most stable isotope, 222rn, has a half-life of only 3.8 days, making radon one of the rarest elements since it decays away so quickly. however, since thorium and uranium are two of the most common radioactive elements on earth, and they have three isotopes with very long half-lives, on the order of several billions of years, radon will be present on earth long into the future in spite of its short half-life as it is continually being generated. the decay of radon produces many other short-lived nuclides known as radon daughters, ending at stable isotopes of lead.[2]

    unlike all the other intermediate elements in the aforementioned decay chains, radon is, under normal conditions, gaseous and easily inhaled. radon gas is considered a health hazard. it is often the single largest contributor to an individual's background radiation dose, but due to local differences in geology,[3] the level of the radon-gas hazard differs from location to location. despite its short lifetime, radon gas from natural sources, such as uranium-containing minerals, can accumulate in buildings, especially, due to its high density, in low areas such as basements and crawl spaces. radon can also occur in ground water – for example, in some spring waters and hot springs.[4]

    epidemiological studies have shown a clear link between breathing high concentrations of radon and incidence of lung cancer. radon is a contaminant that affects indoor air quality worldwide. according to the united states environmental protection agency (epa), radon is the second most frequent cause of lung cancer, after cigarette smoking, causing 21,000 lung cancer deaths per year in the united states. about 2,900 of these deaths occur among people who have never smoked. while radon is the second most frequent cause of lung cancer, it is the number one cause among non-smokers, according to epa policy-oriented estimates.[5] significant uncertainties exist for the health effects of low-dose exposures.[6] unlike the gaseous radon itself, radon daughters are solids and stick to surfaces, such as airborne dust particles, which can cause lung cancer if inhaled.[7]

  • characteristics
  • history and etymology
  • occurrence
  • applications
  • health risks
  • see also
  • references
  • external links

Radon, 86Rn
Radon
Pronunciationn/ (RAY-don)
Appearancecolorless gas
Mass number[222]
Radon in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Xe

Rn

Og
astatineradonfrancium
Atomic number (Z)86
Groupgroup 18 (noble gases)
Periodperiod 6
Blockp-block
Element category  Noble gas
Electron configuration[Xe] 4f14 5d10 6s2 6p6
Electrons per shell2, 8, 18, 32, 18, 8
Physical properties
Phase at STPgas
Melting point202 K ​(−71 °C, ​−96 °F)
Boiling point211.5 K ​(−61.7 °C, ​−79.1 °F)
Density (at STP)9.73 g/L
when liquid (at b.p.)4.4 g/cm3
Critical point377 K, 6.28 MPa[1]
Heat of fusion3.247 kJ/mol
Heat of vaporization18.10 kJ/mol
Molar heat capacity5R/2 = 20.786 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 110 121 134 152 176 211
Atomic properties
Oxidation states0, +2, +6
ElectronegativityPauling scale: 2.2
Ionization energies
  • 1st: 1037 kJ/mol
Covalent radius150 pm
Van der Waals radius220 pm
Color lines in a spectral range
Spectral lines of radon
Other properties
Natural occurrencefrom decay
Crystal structureface-centered cubic (fcc)
Face-centered cubic crystal structure for radon
Thermal conductivity3.61×103  W/(m·K)
Magnetic orderingnon-magnetic
CAS Number10043-92-2
History
DiscoveryErnest Rutherford and Robert B. Owens (1899)
First isolationWilliam Ramsay and Robert Whytlaw-Gray (1910)
Main isotopes of radon
Iso­tope Abun­dance Half-life (t1/2) Decay mode Pro­duct
210Rn syn 2.4 h α 206Po
211Rn syn 14.6 h ε 211At
α 207Po
222Rn trace 3.8235 d α 218Po
224Rn syn 1.8 h β 224Fr
Category Category: Radon
| references

Radon is a chemical element with the symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas. It occurs naturally in minute quantities as an intermediate step in the normal radioactive decay chains through which thorium and uranium slowly decay into lead and various other short-lived radioactive elements; radon itself is the immediate decay product of radium. Its most stable isotope, 222Rn, has a half-life of only 3.8 days, making radon one of the rarest elements since it decays away so quickly. However, since thorium and uranium are two of the most common radioactive elements on Earth, and they have three isotopes with very long half-lives, on the order of several billions of years, radon will be present on Earth long into the future in spite of its short half-life as it is continually being generated. The decay of radon produces many other short-lived nuclides known as radon daughters, ending at stable isotopes of lead.[2]

Unlike all the other intermediate elements in the aforementioned decay chains, radon is, under normal conditions, gaseous and easily inhaled. Radon gas is considered a health hazard. It is often the single largest contributor to an individual's background radiation dose, but due to local differences in geology,[3] the level of the radon-gas hazard differs from location to location. Despite its short lifetime, radon gas from natural sources, such as uranium-containing minerals, can accumulate in buildings, especially, due to its high density, in low areas such as basements and crawl spaces. Radon can also occur in ground water – for example, in some spring waters and hot springs.[4]

Epidemiological studies have shown a clear link between breathing high concentrations of radon and incidence of lung cancer. Radon is a contaminant that affects indoor air quality worldwide. According to the United States Environmental Protection Agency (EPA), radon is the second most frequent cause of lung cancer, after cigarette smoking, causing 21,000 lung cancer deaths per year in the United States. About 2,900 of these deaths occur among people who have never smoked. While radon is the second most frequent cause of lung cancer, it is the number one cause among non-smokers, according to EPA policy-oriented estimates.[5] Significant uncertainties exist for the health effects of low-dose exposures.[6] Unlike the gaseous radon itself, radon daughters are solids and stick to surfaces, such as airborne dust particles, which can cause lung cancer if inhaled.[7]