In nuclear physics, properties of a nucleus depend on evenness or oddness of its atomic number (proton number) Z, neutron number N and, consequently, of their sum, the mass number A. Most importantly, oddness of both Z and N tends to lower the nuclear binding energy, making odd nuclei generally less stable. This effect is not only experimentally observed, but is included in the semi-empirical mass formula and explained by some other nuclear models, such as the nuclear shell model. This difference of nuclear binding energy between neighbouring nuclei, especially of odd-A isobars, has important consequences for beta decay.
The nuclear spin is zero for even-Z, even-N nuclei, integer for all even-A nuclei, and odd half-integer for all odd-A nuclei.
The neutron–proton ratio is not the only factor affecting nuclear stability. Adding neutrons to isotopes can vary their nuclear spins and nuclear shapes, causing differences in neutron capture cross sections and gamma spectroscopy and nuclear magnetic resonance properties. If too many or too few neutrons are present with regard to the nuclear binding energy optimum, the nucleus becomes unstable and subject to certain types of nuclear decay. Unstable nuclides with a nonoptimal number of neutrons or protons decay by beta decay (including positron decay), electron capture, or other means, such as spontaneous fission and cluster decay.
Even-mass-number nuclides, which comprise 150/251 = ~60% of all stable nuclides, are bosons, i.e., they have integer spin. 145 of the 150 are even-proton, even-neutron (EE) nuclides, which necessarily have spin 0 because of pairing. The remainder of the stable bosonic nuclides are five odd-proton, odd-neutron stable nuclides (21H, 63Li, 105B, 147N and 180m73Ta), all having a non-zero integer spin.
Beta decay of an even–even nucleus produces an odd–odd nucleus, and vice versa. An even number of protons or of neutrons are more stable (higher binding energy) because of pairing effects, so even–even nuclei are much more stable than odd–odd. One effect is that there are few stable odd–odd nuclides, but another effect is to prevent beta decay of many even–even nuclei into another even–even nucleus of the same mass number but lower energy, because decay proceeding one step at a time would have to pass through an odd–odd nucleus of higher energy. Double beta decay directly from even–even to even–even skipping over an odd–odd nuclide is only occasionally possible, and even then with a half-life greater than a billion times the age of the universe. For example, the double beta emitter 116Cd has a half-life of 2.9×1019 years. This makes for a larger number of stable even–even nuclides, with some mass numbers having two stable nuclides, and some elements (atomic numbers) having as many as seven.
For example, the extreme stability of helium-4 due to a double pairing of two protons and two neutrons prevents any nuclides containing five or eight nucleons from existing for long enough to serve as platforms for the buildup of heavier elements via nuclear fusion in Big Bang nucleosynthesis; only in stars is there enough time for this (see triple-alpha process). This is also the reason why 84Be decays so quickly into two alpha particles, making beryllium the only even-numbered element that is monoisotopic.
There are 145 stable even–even nuclides, forming ~58% of the 251 stable nuclides. There are also 22 primordial long-lived even–even nuclides. As a result, many of the 41 even-numbered elements from 2 to 82 have many primordial isotopes. Half of these even-numbered elements have six or more stable isotopes. The lightest stable even-even isotope is 42He and the heaviest is 20882Pb. These are also the lightest and heaviest known doubly magic nuclides.[1] 20882Pb is the final decay product of 23290Th,[2] a primordial radionuclide with an even proton and neutron number. 23892U is another notable primordial radionuclide with a half life of 4.468 billion years,[3] and produces almost half of all radioactive heat within the Earth.[4]
All even–even nuclides have spin 0 in their ground state, due to the Pauli exclusion principle (See Pairing Effects for more details).
Only five stable nuclides contain both an odd number of protons and an odd number of neutrons. The first four "odd–odd" nuclides occur in low mass nuclides, for which changing a proton to a neutron or vice versa would lead to a very lopsided proton–neutron ratio (21H, 63Li, 105B, and 147N; spins 1, 1, 3, 1). All four of these isotopes have the same number of protons and neutrons, and they all have an odd number for their nuclear spin. The only other observationally "stable" odd–odd nuclide is 180m73Ta (spin 9), the only primordial nuclear isomer, which has not yet been observed to decay despite experimental attempts.[5] Also, four long-lived radioactive odd–odd nuclides (4019K – the most common radioisotope in the human body,[6][7] 5023V,13857La,17671Lu with spins 4, 6, 5, 7, respectively) occur naturally. As in the case of 180m73Ta decay of high spin nuclides by beta decay (including electron capture), gamma decay, or internal conversion is greatly inhibited if the only decay possible between isobar nuclides (or in the case of 180m73Ta between nuclear isomers of the same nuclide) involves high multiples of a change in spin of 1 unit, the "preferred" change of spin that is associated with rapid decay. This high-spin inhibition of decay is the cause of the five heavy stable or long-lived odd-proton, odd-neutron nuclides discussed above. For an example of this effect where the spin effect is subtracted, tantalum-180, the odd–odd low-spin (theoretical) decay product of primordial tantalum-180m, itself has a half life of only about eleven hours.[8]
Many odd–odd radionuclides (like tantalum-180) with comparatively short half lives are known. Almost invariably, these decay by positive or negative beta decay, in order to produce stable even–even isotopes which have paired protons and paired neutrons. In some odd–odd radionuclides where the ratio of protons to neutrons is neither excessively large nor excessively small (i.e., falling too far from the ratio of maximal stability), this decay can proceed in either direction, turning a proton into a neutron, or vice versa. An example is 6429Cu, which can decay either by positron emission to 6428Ni, or by electron emission to 6430Zn.
Of the nine primordial odd–odd nuclides (five stable and four radioactive with long half lives), only 147N is the most common isotope of a common element. This is the case because proton capture on 147N is the rate-limiting step of the CNO-I cycle. The nuclides 63Li and 105B are minority isotopes of elements that are themselves rare compared to other light elements, while the other six isotopes make up only a tiny percentage of the natural abundance of their elements. For example, 180m73Ta is thought to be the rarest of the 251 stable nuclides.
None of the primordial (i.e., stable or nearly stable) odd–odd nuclides have spin 0 in the ground state. This is because the single unpaired neutron and unpaired proton have a larger nuclear force attraction to each other if their spins are aligned (producing a total spin of at least 1 unit), instead of anti-aligned. See deuterium for the simplest case of this nuclear behavior.
For a given odd mass number, there is exactly one beta-stable nuclide. There is not a difference in binding energy between even–odd and odd–even comparable to that between even–even and odd–odd, leaving other nuclides of the same mass number (isobars) free to beta decay toward the lowest-mass nuclide. For mass numbers of 147, 151, and 209+, the beta-stable isobar of that mass number has been observed to undergo alpha decay. (In theory, mass number 143 to 155, 160 to 162, and 165+ can also alpha decay.) This gives a total of 101 stable nuclides with odd mass numbers. There are another nine radioactive primordial nuclides (which by definition all have relatively long half lives, greater than 80 million years) with odd mass numbers.
Odd-mass-number nuclides are fermions, i.e., have half-integer spin. Generally speaking, since odd-mass-number nuclides always have an even number of either neutrons or protons, the even-numbered particles usually form part of a "core" in the nucleus with a spin of zero. The unpaired nucleon with the odd number (whether proton or neutron) is then responsible for the nuclear spin, which is the sum of the orbital angular momentum and spin angular momentum of the remaining nucleon.
The odd-mass number stable nuclides are divided (roughly evenly) into odd-proton–even-neutron, and odd-neutron–even-proton nuclides, which are more thoroughly discussed below.
These 48 stable nuclides, stabilized by their even numbers of paired neutrons, form most of the stable isotopes of the odd-numbered elements; the very few odd–odd nuclides comprise the others. There are 41 odd-numbered elements with Z = 1 through 81, of which 30 (including hydrogen, since zero is an even number) have one stable odd-even isotope, the elements technetium (43Tc) and promethium (61Pm) have no stable isotopes, and nine elements: chlorine (17Cl), potassium (19K), copper (29Cu), gallium (31Ga), bromine (35Br), silver (47Ag), antimony (51Sb), iridium (77Ir), and thallium (81Tl), have two odd–even stable isotopes each. This makes a total of 30×1 + 9×2 = 48 stable odd–even isotopes. The lightest example of this type of nuclide is 11H (protium) as zero is an even number while the heaviest example is 20581Tl. There are also five primordial long-lived radioactive odd–even isotopes, 8737Rb,[9] 11549In,[10][11] 18775Re,[12] 15163Eu,[13][14] and 20983Bi.[15][16] The last two were only recently found to undergo alpha decay, with half-lives greater than 1018 years.
These 53 stable nuclides have an even number of protons and an odd number of neutrons. By definition, they are all isotopes of even-Z elements, where they are a minority in comparison to the even–even isotopes which are about 3 times as numerous. Among the 41 even-Z elements that have a stable nuclide, only two elements (argon and cerium) have no even–odd stable nuclides. One element (tin) has three. There are 24 elements that have one even–odd nuclide and 13 that have two even–odd nuclides. The lightest example of this type of nuclide is 32He and the heaviest is 20782Pb.
Of 34 primordial radionuclides there exist three even–odd nuclides (see table at right), including the fissile 23592U. Because of their odd neutron numbers, the even–odd nuclides tend to have large neutron capture cross sections, due to the energy that results from neutron-pairing effects.
These stable even-proton odd-neutron nuclides tend to be uncommon by abundance in nature, generally because in order to form and contribute to the primordial abundance, they must have escaped capturing neutrons to form yet other stable even–even isotopes, during both the s-process and r-process of neutron capture, during nucleosynthesis in stars. For this reason, only 19578Pt and 94Be are the most naturally abundant isotopes of their element, the former only by a small margin, and the latter only because the expected beryllium-8 has lower binding energy than two alpha particles and therefore immediately alpha decays.
Actinides with odd neutron numbers are generally fissile (with thermal neutrons), while those with even neutron numbers are generally not, though they are fissionable with fast neutrons. Only 94Be, 147N, and 19578Pt have an odd neutron number and are the most naturally abundant isotope of their element.
{{cite book}}
{{cite journal}}
رامون فونست معلومات شخصية الميلاد 31 أغسطس 1883(1883-08-31)هافانا الوفاة 10 سبتمبر 1959 (76 سنة)هافانا مواطنة كوبا الحياة العملية المهنة مُبارز بالسيف الرياضة مبارزة السلاح تعديل مصدري - تعديل رامون فونست (Ramón Fonst) هو لاعب أولمبي لرياضة مبارزة سيف الشيش من كوبا.[1] شا
Iglesia Presbiteriana San Andrés del Centroold image of the original facade of St. AndrewReligionAffiliationPresbyterianRiteProtestantPatronAndrew the ApostleLocationLocationAv. Belgrano 579, Monserrat, Buenos AiresCountryArgentinaArchitectureArchitect(s)Edwin Arthur MerryCharles RaynesTypeneo-GothicDate established1829Completed1896 Iglesia Presbiteriana San Andrés del Centro (St. Andrew's Scotch Presbyterian Church) is a Presbyterian temple of the city of Buenos Aires.[1] It is locate…
Women's national basketball team representing Macedonia This article is about the women's team. For the men's team, see North Macedonia men's national basketball team. North MacedoniaFIBA ranking75 8 (21 August 2023)[1]Joined FIBA1993FIBA zoneFIBA EuropeNational federationBasketball Federation of North MacedoniaCoachAleksandar AshadanovNickname(s)Лавови (Lions)Црвено-Жолти (Red-Yellows)Фаланга (Phalanx)Olympic GamesAppearancesNoneWorld CupAppearancesNoneEuroB…
American musician and filmmaker Matt FarleyFarley in 2019Background informationBorn (1978-06-03) June 3, 1978 (age 45)OriginDanvers, Massachusetts, U.S.GenresAlternative rock, rock music, folk, novelty songsOccupation(s)Singer-songwriter, musician, filmmakerInstrument(s)Vocals, piano, keyboards, guitarYears active1996–presentLabelsMotern MediaWebsitemoternmedia.comMusical artist Matt Farley (born June 3, 1978)[1] is an American filmmaker, musician, and songwriter who has released …
Satoshi Ōmura Información personalNombre en japonés 大村 智 Nacimiento 12 de julio de 1935 (88 años) Nirasaki, Yamanashi, JapónNacionalidad japonésEducaciónEducación doctorado en ciencias y Doctor of Pharmacy Educado en Universidad de YamanashiInformación profesionalÁrea BioquímicaCargos ocupados Catedrático de universidad Empleador Tokyo Metropolitan Sumida Technical High School (1958-1962)Universidad de Yamanashi (1963-1965)The Kitasato Institute (desde 1965)…
У Вікіпедії є статті про інших людей із прізвищем Маріні. Маріно Маріні Народився 27 лютого 1901(1901-02-27)[1][2][…]Пістоя, Тоскана, Італія[4][5][6] Помер 6 серпня 1980(1980-08-06)[1][2][…] (79 років)В'яреджо, Провінція Лукка, Тоскана, Італія[5][6] Громадянство …
Submarine Chaser No. 36 is at left in this 27 November 1917 photograph of SC-1-class submarine chasers under construction at the New York Navy Yard in Brooklyn, New York. In the center is Submarine Chaser No. 38, and the bow of Submarine Chaser No. 39 is at right. History United States Name USS Submarine Chaser No. 36 (1917-1920) USS SC-36 (1920-1921) BuilderNew York Navy Yard, Brooklyn, New York Commissioned23 January 1918 ReclassifiedSC-36 on 17 July 1920 FateSold 24 June 1921 General characte…
هذه المقالة يتيمة إذ تصل إليها مقالات أخرى قليلة جدًا. فضلًا، ساعد بإضافة وصلة إليها في مقالات متعلقة بها. (مارس 2019) روجر جونستون (بالإنجليزية: Roger Johnston) معلومات شخصية الميلاد 18 يونيو 1930 ملبورن[1] تاريخ الوفاة 24 يونيو 2020 (90 سنة) [2] مواطنة أستراليا مناصب
Thực thi chương trình Khái niệm chung Mã Dịch Trình biên dịch Thời gian biên dịch Trình biên dịch tối ưu Intermediate representation (IR) Thực thi Hệ thống runtime Runtime Thực thi được Trình thông dịch Máy ảo Các loại mã Mã nguồn Mã đối tượng Bytecode Mã máy Microcode Chiến lược biên dịch Just-in-time (JIT) Tracing just-in-time Ahead-of-time (AOT) Transcompilation Recompilation Runtime đáng chú ý Android Runtime (ART) Com…
Ця стаття є частиною Проєкту:Населені пункти України (рівень: невідомий) Портал «Україна»Мета проєкту — покращувати усі статті, присвячені населеним пунктам та адміністративно-територіальним одиницям України. Ви можете покращити цю статтю, відредагувавши її, а на сторін…
Omán está dividido en once gobernaciones (muhafazah) desde el 28 de octubre de 2011.[1][2][3] Cada una de las 11 gobernaciones está dividida en provincias (wilayat). Gobernación Árabe Capital vilayatos Ad Dakhiliyah منطقة الداخلية Nizwa 8 Ad Dhahirah منطقة الظاهرة Ibri 3 Al Batinah Norte محافظة شمال الباطنة Sohar 6 Al Batinah Sur محافظة جنوب الباطنة Rustaq 6 Al Buraymi محافظة البريمي Al Buraymi 3 Al…
Der Titel dieses Artikels ist mehrdeutig. In der Geschichtswissenschaft ist eine Kreuzfahrt im Mittelalter die Teilnahme an einem Kreuzzug. Kreuzfahrtschiffe vor Saint Thomas: Carnival Liberty, Carnival Triumph und Carnival Glory, 2007. Als Kreuzfahrt oder auch Kreuzfahrtreise werden Urlaubsreisen auf einem Kreuzfahrtschiff bezeichnet. Diese erfolgen entlang festgelegter Routen zwischen verschiedenen Häfen an touristisch attraktiven Zielen und sind typischerweise Pauschalreisen. Der Begriff hat…
Rauno Lehtinen Información personalNombre de nacimiento Rauno Väinämö Lehtinen Nacimiento 7 de abril de 1932 Tampere (Finlandia) Fallecimiento 1 de mayo de 2006 (74 años)Helsinki (Finlandia) Nacionalidad FinlandesaLengua materna Finés Información profesionalOcupación Director de orquesta, compositor, maestro de capilla y músico Área Schlager Género Música clásica Distinciones Medalla Pro Finlandia (2000) [editar datos en Wikidata] Rauno Lehtinen (7 de abril de 1932-1 …
هذه المقالة يتيمة إذ تصل إليها مقالات أخرى قليلة جدًا. فضلًا، ساعد بإضافة وصلة إليها في مقالات متعلقة بها. (يونيو 2016) يوكي هاماموتو (باليابانية: 濱本 裕基)[1] معلومات شخصية الميلاد 4 سبتمبر 1985 (العمر 38 سنة)اليابان الجنسية ياباني الحياة المهنية المهنة متسابق دراجات نارية…
Bagian dari seri tentangLGBT lesbian ∙ gay ∙ biseksual ∙ transgender Orientasi seksual Homoseksualitas Gay Lesbian Biseksualitas Panseksualitas Poliseksualitas Aseksualitas Aseksualitas abu-abu Queer Identitas seksual Demografi New York Indonesia Biologi Lingkungan Sejarah Garis waktu Gerakan sosial Interseks dan LGBT Kerusuhan Stonewall Komunitas LGBT Afrika-Amerika Budaya Acara terbesar Desa gay Homososialisasi Hubungan sesama jenis Kebanggaan Pawai ke…
Sebuah masjid di Tokmok. Islam merupakan agama utama di Kirgizstan. Agama di Kirgizstan (2020)[1][2] Islam (90%) Kekristenan (8%) Tidak berafiliasi (2%) Islam merupakan agama utama di Kirgizstan dan konstitusi juga menjamin kebebasan beragama. Kirgizstan merupakan negara multikultural dan multi-agama dengan Islam, Buddhisme, Baháʼí, Kekristenan (yaitu Gereja Ortodoks Rusia, Katolik Roma, Gereja Masehi Advent Hari Ketujuh dan Saksi-Saksi Yehuwa…
هذه المقالة بحاجة لصندوق معلومات. فضلًا ساعد في تحسين هذه المقالة بإضافة صندوق معلومات مخصص إليها. يفتقر محتوى هذه المقالة إلى الاستشهاد بمصادر. فضلاً، ساهم في تطوير هذه المقالة من خلال إضافة مصادر موثوق بها. أي معلومات غير موثقة يمكن التشكيك بها وإزالتها. (يناير 2022) روبوت مف
Lord of Cilicia Constantine ILord of CiliciaConstantine and Tancred at TarsusLord of Armenian CiliciaReign1095 – c. 1100PredecessorRoupen ISuccessorThoros IBorn1045–50Died1102/1103BurialMonastery of CastalonSpouseAn unnamed great-granddaughter of Bardas PhokasIssueThoros IBeatriceLeo IHouseRoupeniansFatherRoupen I Constantine I or Kostandin I (Armenian: Կոնստանտին; 1035–1040[1] – c. 1100[2]) was the second lord of Armenian Cilicia (1095 – c. 1100). He ruled th…
City in Alabama, United States City in Alabama, United StatesMadison, AlabamaCityCity of MadisonThe Madison Historic District was added to the National Register of Historic Places on March 29, 2006.Motto(s): Play hard, learn well & live richlyLocation of Madison in Limestone County and Madison County, Alabama.Coordinates: 34°42′54″N 86°44′23″W / 34.71500°N 86.73972°W / 34.71500; -86.73972CountryUnited StatesStateAlabamaCountiesMadison, LimestoneGovern…
Italian organization Dante Society redirects here. For the American organization, see Dante Society of America. This article includes a list of general references, but it lacks sufficient corresponding inline citations. Please help to improve this article by introducing more precise citations. (September 2013) (Learn how and when to remove this template message) Società Dante AlighieriThe Dante Alighieri Society in La Sabana, Costa RicaFounded1889; 134 years ago (1889)TypeCult…
Lokasi Pengunjung: 18.116.43.95