User:Praseodymium-141/Unbipentium

Unbipentum, also known as element 125 or eka-neptunium, is the hypothetical chemical element in the periodic table with the placeholder symbol of Ubt and atomic number 125. Unbipentium and Ubp are the temporary systematic IUPAC name and symbol respectively, which are used until the element is discovered, confirmed, and a permanent name is decided upon. In the periodic table of the elements, it is expected to follow unbiquadium as the second element of the superactinides and the fifth element of the 8th period. Similarly to unbibium and unbiunium, it is expected to fall within the range of the island of stability.

Since there are no natural isotopes of this element, it would have to be generated (synthesized) in an artificial way through nuclear reactions. The name is provisional and is derived from the ordinal number. As of 2022, the synthesis of unbipentium has only been attempted once, and no naturally occurring isotopes have been found to exist. There are currently no plans to attempt to synthesize unbipentium.

Unbipentium is expected to be in a new group of elements called superactinides. These should behave differently from other groups of elements.

Chemically, unbipentium is expected to show some resemblance to promethium and neptunium. However, due to relativistic effects, some of these properties may differ from expected. Unbipentium is possibly the fifth element to have a G orbital, which would fill the 5th shell with three additional electrons.

History
Every element from mendelevium onward was produced in fusion-evaporation reactions, culminating in the discovery of the heaviest known element oganesson in 2002 and most recently tennessine in 2010. These reactions approached the limit of current technology; for example, the synthesis of tennessine required 22 milligrams of 249Bk and an intense 48Ca beam for six months. The intensity of beams in superheavy element research cannot exceed 1012 projectiles per second without damaging the target and detector, and producing larger quantities of increasingly rare and unstable actinide targets is impractical. Consequently, future experiments must be done at facilities such as the under-construction superheavy element factory (SHE-factory) at the Joint Institute for Nuclear Research (JINR) or RIKEN, which will allow experiments to run for longer stretches of time with increased detection capabilities and enable otherwise inaccessible reactions. Even so, it will likely be a great challenge to continue past elements 120 or perhaps 121 given short predicted half-lives and low predicted cross sections.

Only one sythesis attempt has been made, but there will most likely be none in the near future; the discoveries of elements 119 and 120 as well as new isotopes of known superheavy elements closer to the predicted island of stability are currently more feasible and of greater interest. It may also be possible that fusion-evaporation reactions may not work at all, and new methods of synthesis such as multinucleon transfer or inverse quasi-fission reactions may be required, though the production of lighter superheavy nuclei with 102 < Z < 106 is more favorable, especially if shell effects are weaker than predicted or otherwise nonexistent.

Naming
The name unbipentium (literally meaning one-two-five-ium ) is a systematic element name, used as a placeholder until it is confirmed by other research groups and the IUPAC decides on a name. Usually, the name suggested by the discoverer(s) is chosen. Using Mendeleev's nomenclature for unnamed and undiscovered elements, unbipentium should instead be known as eka-neptunium. However, such an extrapolation might not work for g-block elements with no known congeners, and eka-neptunium would instead refer to element 145 or 147 when the term is meant to denote the element directly below neptunium. After the recommendations of the IUPAC in 1979, the element has since been largely referred to as unbipentium with the atomic symbol of (Ubp), as its temporary name until the element is officially discovered and synthesized, and a permanent name is decided on. Scientists largely ignore this naming convention, and instead simply refer to unbipentium as "element 125" with the symbol of (125), Dvi-promethium, or sometimes even E125 or 125.

Nuclear stability
No superactinide has ever been observed, and it is not known whether the existence of such a heavy atom is physically possible. The stability of nuclei decreases greatly with the increase in atomic number after plutonium, the heaviest primordial element, so that all isotopes with an atomic number above 101 decay radioactively with a half-life under a day, with an exception of dubnium-268. No elements with atomic numbers above 82 (after lead) have stable isotopes. Nevertheless, because of reasons not very well understood yet, there is a slight increased nuclear stability around atomic numbers 110–114, which leads to the appearance of what is known in nuclear physics as the "island of stability". This concept, proposed by University of California professor Glenn Seaborg, explains why superheavy elements last longer than predicted.

In this region of the periodic table, N = 184 and N = 228 have been suggested as closed neutron shells, and various atomic numbers have been proposed as closed proton shells, such as Z = 114, 120, 122, 124, and 126. The island of stability would be characterized by longer half-lives of nuclei located near these magic numbers, though the extent of stabilizing effects is uncertain due to predictions of weakening of the proton shell closures and possible loss of double magicity. More recent research predicts the island of stability to instead be centered at beta-stable copernicium isotopes 291Cn and 293Cn, which would place unbipentium well above the island and result in short half-lives regardless of shell effects.

The layered model of the atomic nucleus predicts the existence of magic numbers per type of nucleons due to the stratification of neutrons and protons in quantum energy levels in the nucleus postulated by this model, as is what it happens for the electrons at the level of the atom; one of these magic numbers is 126, observed for neutrons but not yet for protons, while the following magic number, 184, has never been observed: nuclides with around 126 protons are expected to be (unbihexium) and 184 neutrons are appreciably more stable than neighboring nuclides, with perhaps half-lives greater than a second, which would constitute an "island of stability". The difficulty is that, for superheavy atoms, the determination of the magic numbers seems more delicate than for the light atoms, so that, according to the models, the following magic number should be sought for Z between 114 and 126. The unbipentium is one of the elements that would be possible to produce, with current techniques, in the island of stability; the particular stability of these isotopes would be due to a quantum coupling effect of ω mesons, one of the nine so-called “tasteless” mesons.

Chemical properties
Unbipentium is expected to be the fifth member of a superactinide series. It should have similarities to promethium and neptunium. It is also predicted to be the fifth member of a new block of valence g-electron atoms, although the 5g orbital is not expected to start filling until unbipentium. In the superactinide series, the Aufbau principle is expected to break down due to relativistic effects, and an overlap of the 5g, 6f, 7d, and 8p orbitals is expected, rendering predictions of chemical and atomic properties of these elements very difficult.

Synthesis attempts
The synthesis of unbipentium was first attempted in 1977 by bombarding a target of americium-238 with zinc-65 ions at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany: No atoms were identified.
 * 243Am + 66,68Zn → 309,311Ubp