High Quality Content by WIKIPEDIA articles! Naturally occurring tungsten (atomic symbol W) consists of four stable isotopes (182W, 183W, 184W, and 186W) and one isotope, 180W, with an extremely long half-life of 1.8 ± 0.2 Ea (1018 years). On average, two alpha decays of 180W occur per gram of natural tungsten per year.
High Quality Content by WIKIPEDIA articles! Ununpentium (Uup) is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 288Uup in 2004. There are four known radioisotopes from 287Uup to 290Uup. The longest-lived isotope is 289Uup with a half-life of 220 ms.
High Quality Content by WIKIPEDIA articles! There are 39 known isotopes of radon (Rn) from 193Rn to 231Rn. The most stable isotope is 222Rn with a half-life of 3.823 days. Four isotopes, 218, 219, 220, 222Rn occur in trace quantities in nature as decay products of, respectively, 218At, 223Ra, 224Ra, and 226Ra. 218Rn and 222Rn are intermediate steps in the decay chain for 238U, 219Rn is an intermediate step in the decay chain for 235U and 220Rn occurs in the decay chain for 232Th.
High Quality Content by WIKIPEDIA articles! Naturally occurring xenon (Xe) is made of nine stable isotopes. (124Xe, 126Xe, 134Xe and 136Xe are predicted to undergo double beta decay, but this has never been observed, so they are considered to be stable.) Xenon has the second highest number of stable isotopes. Only tin, with 10 stable isotopes, has more. Beyond these stable forms, there are over 40 unstable isotopes and isomers that have been studied, the longest-lived of which is 127Xe with a half-life of 36.345 days. Of known isomers, the longest-lived is 131mXe with a half-life of 11.934 days. 129Xe is produced by beta decay of 129I (half-life: 16 million years); 131mXe, 133Xe, 133mXe, and 135Xe are some of the fission products of both...
High Quality Content by WIKIPEDIA articles! Tin (Sn) is the element with the greatest number of stable isotopes (ten) (three of them are potentially radioactive but have not been observed to decay), which is probably related to the fact that 50 is a "magic number" of protons. 29 additional unstable isotopes are known, including the "doubly magic" tin-100 (100Sn) (discovered in 1994) and tin-132 (132Sn). The longest-lived radioisotope is 126Sn with a half-life of 230,000 years. All other radioisotopes have half-lives less than a year.
High Quality Content by WIKIPEDIA articles! Francium (Fr) has no stable isotopes. A standard atomic mass cannot be given. Its most stable isotope is 223Fr with a half-life of 22 minutes, occurring in trace quantities as an intermediate decay product of 235U. The other natural isotope is 221Fr.
High Quality Content by WIKIPEDIA articles! There are 33 known isotopes of molybdenum (Mo) ranging in atomic mass from 83 to 115, as well as four metastable nuclear isomers. Seven isotopes occur naturally, with atomic masses of 92, 94, 95, 96, 97, 98, and 100. Of these naturally occurring isotopes, six (all but 100Mo) have never been observed to decay, but all are theoretically capable of radioactive decay. All unstable isotopes of molybdenum decay into isotopes of zirconium, niobium, technetium, and ruthenium.
High Quality Content by WIKIPEDIA articles! Radium (Ra) has no stable or nearly stable isotopes, and thus a standard atomic mass cannot be given. The longest lived, and most common, isotope of radium is 226Ra with a half-life of 1600 years. 226Ra occurs in the decay chain of 238U (often referred to as the radium series.) Radium has 35 known isotopes from 201Ra to 235Ra, with the newest being 235Ra.
High Quality Content by WIKIPEDIA articles! Actinium (Ac) has no stable isotopes, thus a standard atomic mass cannot be given. There are 31 known isotopes, from 206Ac to 236Ac, and 2 isomers. Two isotopes are found in nature, 227Ac and 228Ac, as intermediate decay products of, respectively, 235U and 232Th. 228Ac is extremely rare, and almost all natural actinium is 227Ac.
High Quality Content by WIKIPEDIA articles! Americium (Am) is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 241Am in 1944.
High Quality Content by WIKIPEDIA articles! Ununtrium (Uut) is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 284Uut as a decay product of 288Uup in 2003. The first isotope to be directly synthesized was 278Uut in 2004. There are 6 known radioisotopes from 278Uut to 286Uut. The longest-lived isotope is 286Uut with a half-life of 19.6 seconds.
High Quality Content by WIKIPEDIA articles! Bohrium (Bh) is an artificial element, and thus a standard atomic mass cannot be given. Like all artificial elements, it has no stable isotopes. The first isotope to be synthesized was 262Bh in 1981. There are 11 known isotopes ranging from 260Bh to 274Bh, and 1 isomer, 262mBh. The longest-lived isotope is 270Bh with a half-life of 1 minute.
High Quality Content by WIKIPEDIA articles! There are seven stable isotopes of mercury (Hg) with 202Hg being the most abundant (29.86%). The longest-lived radioisotopes are 194Hg with a half-life of 444 years, and 203Hg with a half-life of 46.612 days. Most of the remaining radioisotopes have half-lives that are less than a day. 199Hg and 201Hg are the most often studied NMR-active nuclei, having spins of 1/2 and 3/2 respectively.
High Quality Content by WIKIPEDIA articles! Naturally occurring ruthenium (Ru) is composed of seven stable isotopes. Additionally, 27 radioactive isotopes have been discovered. Of these radioisotopes, the most stable are 106Ru with a half-life of 373.59 days, 103Ru with a half-life of 39.26 days and 97Ru with a half-life of 2.9 days.
High Quality Content by WIKIPEDIA articles! Rubidium (Rb) has 32 isotopes, with naturally occurring rubidium being composed of just two isotopes; 85Rb (72.2%) and the radioactive 87Rb (27.8%). Normal mixes of rubidium are radioactive enough to fog photographic film in approximately 30 to 60 days. Standard atomic mass is 85.4678(3) u.
High Quality Content by WIKIPEDIA articles! Polonium (Po) has 33 isotopes, all of which are radioactive, with between 186 and 227 nucleons. 210Po with a half-life of 138.376 days has the longest half-life of naturally occurring polonium. 209Po with a half-life of 103 years has the longest half-life of all isotopes of polonium. 209Po and 208Po (half-life 2.9 years) can be made through the alpha, proton, or deuteron bombardment of lead or bismuth in a cyclotron.