roentgenium

Ed note: Named roentgenium subsequent to this noder's posting.

It's in the last column of the transition metals on the periodic table, just like copper, silver, and gold. Note that the other three elements get more rare and valuable as they go down - but not even gold comes close to how valuable unununium is. Sure, there's only something like 100,000 cubic meters of gold on Earth, which in the proper perspective is not all that much, but only a few atoms of unununium have ever been made. Given how expensive the scientific equipment to make it is, I'd say it's worth several thousand dollars per atom, at least.

Of course, it's radioactive. So I guess you're better off having gold.

It will eventually have a different name and a chemical symbol, which is sad because Uuu looks nifty and unununium is fun as hell to type.

Roentgenium
Atomic Symbol Rg
Atomic Number 111
Atomic Weight 272
presumably a solid at 298 K
Color unknown, but probably metallic and silvery white or grey in appearance

Roentgenium is a synthetic element that is not present in the environment. Isolation of an observable quantity of roentgenium has never been achieved, and thus roentgenium has no known uses. The reactivity of roentgenium is unknown, but is assumed to be similar to gold and silver.

Roentgenium was first synthesized on December 8, 1994 at the Gesellschaft für Schwerionenforschung a.k.a the Institute for Heavy Ion Research a.k.a. GSI in Darmstadt, Germany, producing three atoms in an 18 day experiment using their heavy ion accelerator UNILAC, via
Bismuth(209) + Nickel(64) = Roentgenium(272) + 1 neutron

Originally named unununium, element 111 was renamed roentgenium on November 1, 2004, in honor of Wilhelm Roentgen. It is also sometimes referred to as eka-gold.

There are three known isotopes of roentgenium
²⁸⁰Rg with a half life of 3.6 seconds
²⁷⁹Rg with a half life of 170 milliseconds
²⁷²Rg with a half life of 1.5 milliseconds

                    gold
                     ^
darmstadtium <-- roentgenium --> Copernicium

Nov. 4, 2011. London, England The General Assembly of the International Union of Pure and Applied Physics (IUPAP) approved the names of the new elements roentgenium (Rg, element 111), as well as two other elements, darmstadtium (Ds, element 110), and copernicium (Cn, element 112).

The new element was created in Darmstadt, Germany at the GSI, the Center for Heavy Ion Research, in 1994, when nine atoms were made. It took another 6 years to produce a second batch. It took fifteen years for the international committee to accept the name of the new element.

Roentgenium contains 111 protons and has an atomic weight of 281, which is the same nominal atomic weight as for darmstadtium, (Ds, 110). It was created by a linear accelerator bombarding bismuth ion targets with nickel ions. (The bismuth atoms have to be stripped of their electrons to overcome the problem of electron cloud coulombic repulsion.) GSI's 120 meter long particle accelerator was used to smash the ions together. Detectors studied the detritus of the after-collision spray of emitted particles, and when it detected . Three atoms (all of the isotope ²⁷²Rg) were created in that initial creation process.

The speed of bombardment is crucial. The ballistic ions have to be fast enough to overcome Coulombic repulsion between the positively charged protons in the nuclei of the 'bullets' and the target - but not so fast that the target ions' nuclei are split. Nuclear physicists have prediction models that enable them to predict the range of energies of the ballistic ions that will be able to bind with the target ions' nuclei without splitting them.

The method of nucleus fusion is called "cold fusion". "These are processes which create compound nuclei at low excitation energy (~10–20 MeV, hence "cold"), leading to a higher probability of survival from fission. The excited nucleus then decays to the ground state via the emission of one or two neutrons only."

²⁰⁹₈₃B + ⁶⁴₂₈Ni → ²⁷²₁₁₁Rg + neutron

(This method has nothing to do with the more widely known Pons & Fleischman cold fusion reaction that caused such a controversy in 1989.)

An international committee consisting of members of IUPAP and IUPAC concluded that the initial report by Hofman, et al, was not sufficient to validate GSI's claim to have created a new element ²⁷²111. The IUPAP/IUPAC language is fussy, but that's what science is. In contrast to the case of darmstadtium, where the committee concluded that the work was repeatable and conclusive, this case did not meet with science's high standards. Here is the language of the final report:

"In bombardments of ²⁰⁹Bi targets with 64Ni using the velocity selector SHIP facility to discriminate in favor of the fused product, ²⁷³111, three sets of localized alpha-decay chains were observed with position-sensitive detectors. The origin was assigned to the isotope ²⁷²111, one neutron removed from the compound nucleus.

"Applying criteria to the case of element 111, the data are of the highest quality. However, there is internal redundancy with just two pairs of data. Chains 2 and 3 have mutually concordant alpha energies, but ones ascribed to the previously unknown ²⁶⁴Bh. Chains 1 and 3 also have mutually concordant alpha energies, but these are ascribed to the previously unknown ²⁶⁸Mt. There is no redundancy involving properties of known daughters for verification purposes.

"Assignment of members of each full chain, unlike the examples of elements 107–109, is burdened by the profuse need to invoke (uncertain) isomeric states with different alpha energies and different lifetimes.

"For example, ²⁷²111 decays to two isomeric states of ²⁶⁸Mt; ²⁶⁸Mt decays to two isomeric states of ²⁶⁴Bh; ²⁶⁴Bh possibly decays to two isomeric states of ²⁶⁰Db, only one of which agrees well with the known decay of ²⁶⁰Db. ²⁶⁰Db decays to ²⁵⁶Lr, but the sole observation with a concordant decay energy occurred with a time delay of 66 s. Although statistically consistent with the known mean-life(35 s), the value is arguably sufficiently convincing.

P. J. KAROL et al., © 2001 IUPAC, Pure and Applied Chemistry 73, 959–967, 962

"For chain 1, two of its four alphas have insufficient energy information and the third alpha is of sufficiently different energy and lifetime compared to chains 2 and 3 to make the sequence assignment fragile.

"Chain 2 is most compelling, matching the known ²⁶⁰Db energy and lifetime. Unambiguous observation of its daughter ²⁵⁶Lr in this sequence would have been sufficient to secure the discovery.

"Chain 3 has a mismatch in ²⁶⁰Db’s alpha energy compared to event 2; its daughter appears quite late (66 s) compared to the known 35 s mean-life; and the second full alpha energy (10.221 MeV) disagrees with that of event 2’s second full alpha energy (10.097 MeV).

"JWP ASSESSMENT: The results of this study are definitely of high quality but there is insufficient internal redundancy to warrant certitude at this stage. Confirmation by further results is needed to assign priority of discovery to this collaboration."

GSI repeated the experiment in 2002 and generated another three atoms of Rn. The Joint Working Group (JWG) of IUPAP/IUPAC concluded that the second test was sufficient to validate GSI's claim to have created a new element.

Roentgenium, which had formerly been named unununium (Uu), is a member of Group 11 in the periodic table, along with copper (₂₉Cu), silver (₄₇Ag), and gold (₇₉Au). Too few atoms have been made to test for bulk properties, but Group 11 elements are known for their malleability and high conductivity.

The heavier members of this group are well known for their lack of reactivity or noble character. Silver and gold are both inert to oxygen, but are attacked by the halogens. In addition, silver is attacked by sulfur and hydrogen sulfide, highlighting its higher reactivity compared to gold. Roentgenium is expected to be even more noble than gold and can be expected to be inert to oxygen and halogens. The most-likely reaction is with fluorine to form a trifluoride, RgF3.

Eleven isotopes have been discovered; their half lives range from 26 seconds (²⁸¹Rg) to 1.6 milliseconds.

God help me. I love science.

Everything2 Writeups: Articles on Chemistry, the Periodic Table, and new elements

1. Ford Prefect, Roentgenium, June 2000
2. avjewe, Roentgenium, Jun. 2001
3. non-buzzard, Periodic Table of the Elements, May, 2002
4. rfc1394, Periodic Table of the Elements, Apr, 2001

Internet References

1. Wikipedia, "Roentgenium"
2. About.com, "Roentgenium"
3. Visual Elements, Roentgenium
4. IUPAC, "Element 111 is named roentgenium," press release, Nov. 8, 2011. IUPAC is the International Union of Pure and Applied Chemistry.
5. Physics News, "A cluster of Physics News articles on roentgenium," If you're a physics news junkie, and who isn't, you need to keep your eye on Physics News.
6. Daniel Cooper, "New periodic table element names confirmed, textbook makers sigh in relief," engadget, Nov. 8, 2011. There's no reason the science news guys can't have a little bit of fun with this.
7. Web Elements, "Roentgenium"
8. Periodic Table of Videos, "Roentgenium." A YouTube video presented by the University of Nottingham giving history, how Roentgenium was created, properties, etc.
9. International Union of Pure and Applied Chemistry, "On the Discovery of the Elements 110-112", IUPAC Technical Report, Pure Appl. Chem., Vol. 73, No. 6, 2001