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Oganesson is a synthetic chemical element; it has symbol Og and atomic number 118. It was first synthesized in 2002 at the Joint Institute for Nuclear Research (JINR) in Dubna, near Moscow, Russia, by a joint team of Russian and American scientists. In December 2015, it was recognized as one of four new elements by the Joint Working Party of the international scientific bodies IUPAC and IUPAP. It was formally named on 28 November 2016. The name honors the nuclear physicist Yuri Oganessian, who played a leading role in the discovery of the heaviest elements in the periodic table. It is one of only two elements named after a person who was alive at the time of naming, the other being seaborgium, and the only element whose eponym is alive as of 2024.
Moscovium is a synthetic chemical element; it has symbol Mc and atomic number 115. It was first synthesized in 2003 by a joint team of Russian and American scientists at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia. In December 2015, it was recognized as one of four new elements by the Joint Working Party of international scientific bodies IUPAC and IUPAP. On 28 November 2016, it was officially named after the Moscow Oblast, in which the JINR is situated.
There are seven stable isotopes of mercury (80Hg) 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 40 radioisotopes have half-lives that are less than a day. 199Hg and 201Hg are the most often studied NMR-active nuclei, having spin quantum numbers of 1/2 and 3/2 respectively. All isotopes of mercury are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed. These isotopes are predicted to undergo either alpha decay or double beta decay.
Naturally occurring platinum (78Pt) consists of five stable isotopes (192Pt, 194Pt, 195Pt, 196Pt, 198Pt) and one very long-lived (half-life 4.83×1011 years) radioisotope (190Pt). There are also 34 known synthetic radioisotopes, the longest-lived of which is 193Pt with a half-life of 50 years. All other isotopes have half-lives under a year, most under a day. All isotopes of platinum are either radioactive or observationally stable, meaning that they are predicted to be radioactive but no actual decay has been observed. Platinum-195 is the most abundant isotope.
Naturally occurring tungsten (74W) consists of five isotopes. Four are considered stable (182W, 183W, 184W, and 186W) and one is slightly radioactive, 180W, with an extremely long half-life of 1.8 ± 0.2 exayears (1018 years). On average, two alpha decays of 180W occur per gram of natural tungsten per year, so for most practical purposes, 180W can be considered stable. Theoretically, all five can decay into isotopes of element 72 (hafnium) by alpha emission, but only 180W has been observed to do so. The other naturally occurring isotopes have not been observed to decay (they are observationally stable), and lower bounds for their half-lives have been established:
Natural hafnium (72Hf) consists of five observationally stable isotopes (176Hf, 177Hf, 178Hf, 179Hf, and 180Hf) and one very long-lived radioisotope, 174Hf, with a half-life of 7.0×1016 years. In addition, there are 34 known synthetic radioisotopes, the most stable of which is 182Hf with a half-life of 8.9×106 years. This extinct radionuclide is used in hafnium–tungsten dating to study the chronology of planetary differentiation.
Naturally occurring erbium (68Er) is composed of 6 stable isotopes, with 166Er being the most abundant. 39 radioisotopes have been characterized with between 74 and 112 neutrons, or 142 to 180 nucleons, with the most stable being 169Er with a half-life of 9.4 days, 172Er with a half-life of 49.3 hours, 160Er with a half-life of 28.58 hours, 165Er with a half-life of 10.36 hours, and 171Er with a half-life of 7.516 hours. All of the remaining radioactive isotopes have half-lives that are less than 3.5 hours, and the majority of these have half-lives that are less than 4 minutes. This element also has numerous meta states, with the most stable being 167mEr.
Natural holmium (67Ho) contains one observationally stable isotope, 165Ho. The below table lists 36 isotopes spanning 140Ho through 175Ho as well as 33 nuclear isomers. Among the known synthetic radioactive isotopes; the most stable one is 163Ho, with a half-life of 4,570 years. All other radioisotopes have half-lives not greater than 1.117 days in their ground states, and most have half-lives under 3 hours.
Naturally occurring praseodymium (59Pr) is composed of one stable isotope, 141Pr. Thirty-eight radioisotopes have been characterized with the most stable being 143Pr, with a half-life of 13.57 days and 142Pr, with a half-life of 19.12 hours. All of the remaining radioactive isotopes have half-lives that are less than 5.985 hours and the majority of these have half-lives that are less than 33 seconds. This element also has 15 meta states with the most stable being 138mPr, 142mPr and 134mPr.
Naturally occurring cerium (58Ce) is composed of 4 stable isotopes: 136Ce, 138Ce, 140Ce, and 142Ce, with 140Ce being the most abundant and the only one theoretically stable; 136Ce, 138Ce, and 142Ce are predicted to undergo double beta decay but this process has never been observed. There are 35 radioisotopes that have been characterized, with the most stable being 144Ce, with a half-life of 284.893 days; 139Ce, with a half-life of 137.640 days and 141Ce, with a half-life of 32.501 days. All of the remaining radioactive isotopes have half-lives that are less than 4 days and the majority of these have half-lives that are less than 10 minutes. This element also has 10 meta states.
Naturally occurring lanthanum (57La) is composed of one stable (139La) and one radioactive (138La) isotope, with the stable isotope, 139La, being the most abundant (99.91% natural abundance). There are 39 radioisotopes that have been characterized, with the most stable being 138La, with a half-life of 1.02×1011 years; 137La, with a half-life of 60,000 years and 140La, with a half-life of 1.6781 days. The remaining radioactive isotopes have half-lives that are less than a day and the majority of these have half-lives that are less than 1 minute. This element also has 12 nuclear isomers, the longest-lived of which is 132mLa, with a half-life of 24.3 minutes. Lighter isotopes mostly decay to isotopes of barium and heavy ones mostly decay to isotopes of cerium. 138La can decay to both.
Antimony (51Sb) occurs in two stable isotopes, 121Sb and 123Sb. There are 35 artificial radioactive isotopes, the longest-lived of which are 125Sb, with a half-life of 2.75856 years; 124Sb, with a half-life of 60.2 days; and 126Sb, with a half-life of 12.35 days. All other isotopes have half-lives less than 4 days, most less than an hour.
Naturally occurring rhodium (45Rh) is composed of only one stable isotope, 103Rh. The most stable radioisotopes are 101Rh with a half-life of 3.3 years, 102Rh with a half-life of 207 days, and 99Rh with a half-life of 16.1 days. Thirty other radioisotopes have been characterized with atomic weights ranging from 88.949 u (89Rh) to 121.943 u (122Rh). Most of these have half-lives that are less than an hour except 100Rh and 105Rh. There are also numerous meta states with the most stable being 102mRh (0.141 MeV) with a half-life of about 3.7 years and 101mRh (0.157 MeV) with a half-life of 4.34 days.
Natural yttrium (39Y) is composed of a single isotope yttrium-89. The most stable radioisotopes are 88Y, which has a half-life of 106.6 days and 91Y with a half-life of 58.51 days. All the other isotopes have half-lives of less than a day, except 87Y, which has a half-life of 79.8 hours, and 90Y, with 64 hours. The dominant decay mode below the stable 89Y is electron capture and the dominant mode after it is beta emission. Thirty-five unstable isotopes have been characterized.
Arsenic (33As) has 33 known isotopes and at least 10 isomers. Only one of these isotopes, 75As, is stable; as such, it is considered a monoisotopic element. The longest-lived radioisotope is 73As with a half-life of 80 days. Arsenic has been proposed as a "salting" material for nuclear weapons. A jacket of 75As, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope 76As with a half-life of 1.0778 days and produce approximately 1.13 MeV gamma radiation, significantly increasing the radioactivity of the weapon's fallout for several hours. Such a weapon is not known to have ever been built, tested, or used.
Naturally occurring zinc (30Zn) is composed of the 5 stable isotopes 64Zn, 66Zn, 67Zn, 68Zn, and 70Zn with 64Zn being the most abundant. Twenty-five radioisotopes have been characterised with the most abundant and stable being 65Zn with a half-life of 244.26 days, and 72Zn with a half-life of 46.5 hours. All of the remaining radioactive isotopes have half-lives that are less than 14 hours and the majority of these have half-lives that are less than 1 second. This element also has 10 meta states.
Naturally occurring vanadium (23V) is composed of one stable isotope 51V and one radioactive isotope 50V with a half-life of 2.71×1017 years. 24 artificial radioisotopes have been characterized (in the range of mass number between 40 and 65) with the most stable being 49V with a half-life of 330 days, and 48V with a half-life of 15.9735 days. All of the remaining radioactive isotopes have half-lives shorter than an hour, the majority of them below 10 seconds, the least stable being 42V with a half-life shorter than 55 nanoseconds, with all of the isotopes lighter than it, and none of the heavier, have unknown half-lives. In 4 isotopes, metastable excited states were found (including 2 metastable states for 60V), which adds up to 5 meta states.
Naturally occurring scandium (21Sc) is composed of one stable isotope, 45Sc. Twenty-five radioisotopes have been characterized, with the most stable being 46Sc with a half-life of 83.8 days, 47Sc with a half-life of 3.35 days, and 48Sc with a half-life of 43.7 hours and 44Sc with a half-life of 3.97 hours. All the remaining isotopes have half-lives that are less than four hours, and the majority of these have half-lives that are less than two minutes, the least stable being proton unbound 39Sc with a half-life shorter than 300 nanoseconds. This element also has 13 meta states with the most stable being 44m2Sc.
The standard atomic weight of a chemical element (symbol Ar°(E) for element "E") is the weighted arithmetic mean of the relative isotopic masses of all isotopes of that element weighted by each isotope's abundance on Earth. For example, isotope 63Cu (Ar = 62.929) constitutes 69% of the copper on Earth, the rest being 65Cu (Ar = 64.927), so
Chemical elements may be named from various sources: sometimes based on the person who discovered it, or the place it was discovered. Some have Latin or Greek roots deriving from something related to the element, for example some use to which it may have been put.
References
- ↑ "Discovery of Elements with Atomic Number Z > 112". Archived from the original on 2012-08-24.
- ↑ Loss, Robert D.; Corish, John (2012-06-26). "Names and symbols of the elements with atomic numbers 114 and 116 (IUPAC Recommendations 2012)" (PDF). Pure and Applied Chemistry. 84 (7): 1669–1672. doi:10.1351/PAC-REC-11-12-03. ISSN 1365-3075.
- ↑ Karol, P.J.; Nakahara, H.; Petley, B.W.; Vogt, E. (2003). "On the Claims for Discovery of Elements 110, 111, 112, 114, 116, and 118 (IUPAC Technical Report)" (PDF). Pure and Applied Chemistry. 75 (10): 1601–1611.
- ↑ "Discovery of the elements with atomic numbers greater than or equal to 113 (IUPAC Technical Report)" (PDF). Pure and Applied Chemistry. 83 (9): 1801. 2011-08-19. doi:10.1351/PAC-REP-10-05-01_errata. ISSN 1365-3075.
- ↑ "General Assembly - IUPAP: The International Union of Pure and Applied Physics". 2021-02-22. Retrieved 2024-03-11.
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