radon

• POS: Noun
• HYPHEN: ra=don

CIDE DICTIONARY

radon, n. 

 An intensely radioactive gaseous element produced by the radioactive decay of radium-226, which is the main isotope of radium found in pitchblende. Chemically it is an inert noble gas. Its atomic symbol is Rn. It has an atomic number of 86. The radon isotope produced by decay of radium has an atomic weight of 222.017, and this isotope decays by alpha emission with a half-life of 3.82 days. Numerous other isotopes have been observed, all radioactive and all having half-lives shorter than that of radon-222. Radon was discovered by M. and Mme. Curie, of Paris, in their studies of the radioactive substances in pitchblende. Radon was originally called radium emanation or exradio.  [PJC]

OXFORD DICTIONARY

radon, n. Chem. a gaseous radioactive inert element arising from the disintegration of radium, and used in radiotherapy.

Usage

Symb.: Rn.

Etymology

RADIUM after argon etc.

ROGET THESAURUS

radon

Calefaction

N calefaction, increase of temperature, heating, calefaction, tepefaction, torrefaction, melting, fusion, liquefaction, burning, ambustion, combustion, incension, accension, concremation, cremation, scorification, cautery, cauterization, ustulation, calcination, cracking, refining, incineration, cineration, carbonization, cupellation, ignition, inflammation, adustion, flagration, deflagration, conflagration, empyrosis, incendiarism, arson, auto dafe, boiling, coction, ebullition, estuation, elixation, decoction, ebullioscope, geyser, distillation (vaporization), furnace, blanket, flannel, fur, wadding, clothing, still, refinery, fractionating column, fractionating tower, cracking tower, match, incendiary, petroleuse, cauterizer, caustic, lunar caustic, alkali, apozem, moxa, acid, aqua fortis, aqua regia, catheretic, nitric acid, nitrochloro-hydric acid, nitromuriatic acid, radioactivity, gamma rays, alpha particles, beta rays, X-rays, radiation, cosmic radiation, background radiation, radioactive isotopes, tritium, uranium, plutonium, radon, radium, sunstroke, coup de soleil, insolation, pottery, ceramics, crockery, porcelain, china, earthenware, stoneware, pot, mug, terra cotta, brick, clinker, cinder, ash, scoriae, embers, soot, slag, coke, carbon, charcoal, wood alcohol, turpentine, tea tree oil, gasoline, kerosene, naptha, fuel oil (fuel), wax, paraffin, residue, tar, inflammability, combustibility, diathermancy, transcalency, conduction, convection, radiation, radiant heat, heat conductivity, conductivity, thermal expansion, coefficient of expansion, heated, molten, sodden, r_echauff_e, heating, adust, inflammable, combustible, diathermal, diathermanous, burnt, volcanic, radioactive.