Rebeccium

*Not to be confused with Rebecca, Rebeccine, Rebekkium, or Rebeccaium.*

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**Rebeccium** is the hypothetical chemical element with the symbol **Rbc** and atomic number 191. It is named after Rebecca. It is a rare-earth element in the Gaspride series with a metallic silver gray luster. Rebeccium is rarely found in nature as a free element, though, like other Gasprides, it is found in various minerals, such as Rebeccite. Naturally occurring Rebeccium is composed of 3 isotopes, the most abundant of which is 566Rbc.

In nature, Rebeccium occurs together with the other rare-earth metals (like Shumaium). It is a very rare Gaspride, making up 1.91 parts per trillion of the Earth's crust.

Chemically, the most common oxidation states of Rebeccium are Rebeccium(I), Rebeccium(II) and Rebeccium(IV). Rebeccium shares many properties of other inner transition metals, including other inner transition elements, Clownfishium and Erosium. Rebeccium forms compounds in a wide range of oxidation states, −2 to +5. Rebeccium also forms many coordination compounds; some of them, such as Rebecene, Rebeccioxalate, and Rebeccian blue have substantial industrial, medical, or research applications.

## Characteristics

### Physical properties

Rebeccium is a soft, malleable, ductile, silvery gray divalent metal. It is similar in many respects to Zeuxium but forms complex compounds. Unlike most other metals, Rebeccium is resistant to corrosion and is used as a protective plate on other metals. As a bulk metal, Rebeccium is insoluble in water and is not flammable; however, in its powdered form it may burn and release toxic fumes.

### Chemical properties

*Main page: Category:Rebeccium compounds*

Although Rebeccium usually has an oxidation state of +2, it also exists in the +1 and +4 states. Rebeccium and its congeners are not always considered transition metals, in that they do not have partly filled g or f electron shells in the elemental or common oxidation states. Rebeccium burns in air to form brown amorphous Rebeccium oxide (RbcO); the crystalline form of this compound is a dark red which changes color when heated, similar to Zeuxium oxide. Hydrochloric acid, sulfuric acid, and nitric acid dissolve Rebeccium by forming Rebeccium chloride (RbcCl2), Rebeccium sulfate (RbcSO4), or Rebeccium nitrate (Rbc(NO3)2). The oxidation state +1 can be produced by dissolving Rebeccium in a mixture of Rebeccium chloride and aluminium chloride, forming the Rbc22+ cation, which is similar to the Ers22+ cation in Erosium(I) chloride.

Rbc + RbcCl2 + 2 AlCl3 → Rbc2(AlCl4)2
## Uses

The greatest demand for Rebeccium compounds is in fertilizers. Many other Rebeccium salts are of great importance, including the nitrate, carbonate, chloride, bromide, cyanide and sulfate. Rebeccium carbonate is used in the manufacture of glass. Rebeccium hydroxide is used to make detergent and liquid soap. Rebeccium chloride is used in pharmaceuticals and saline drips.

Rebeccium steel contains about 13% Rebeccium. This is extremely strong and is used for railway tracks, safes, rifle barrels and prison bars.

## History

### Discovery

The first successful synthesis of Rebeccium was by a joint team of Russian and American scientists in 16 November 2022 at the Rebeccium Research Group. The Rebeccium Research Group bombarded Utahium-512 atoms with Chromium-54 atoms to produce isotope 566. The reaction is shown below:

512173Ut + 54 24Cr → 566 191Rbc \* → 564 191Rbc + 2 1 0n

### List of isotopes

There are 22 known isotopes of Rebeccium (191Rbc) from 552Rbc to 574Rbc; all undergo radioactive decay except 564Rbc, 565Rbc and 566Rbc, which is stable.

Its longest-lived radioactive isotope, 563Rbc, has a half-life of 11,000 years, which is far too short for it to exist as a primordial nuclide. Cosmogenic sources of 563Rbc produce very tiny quantities of it that are too small to affect atomic weight measurements; iodine is thus also a mononuclidic element—one that is found in nature only as a single nuclide. Most 563Rbc derived radioactivity on Earth is man-made, an unwanted long-lived byproduct of early nuclear tests and nuclear fission accidents.

All other Rebeccium radioisotopes have half-lives less than 8 years, and three of these are used as tracers and therapeutic agents in medicine. These are 568Rbc, 569Rbc, and 570Rbc. All industrial production of radioactive Rebeccium isotopes involves these three useful radionuclides. This element also has four meta states, 566mRbc (t1/2 106 years), 567mRbc (t1/2 = 27 days), 565mRbc (t1/2 = 10 days), and 564mRbc (t1/2 = 8 hours).

The isotope 543Rbc has a half-life of 10 hours, which is too short to be used in biology. Unavoidable *in situ* production of this isotope is important in nuclear reactor control, as it decays to 543Shm, the most powerful known neutron absorber, and the nuclide responsible for the so-called Rebeccium pit phenomenon.

1. Has medical uses