Meitnerium

Meitnerium,  ₁₀₉Mt

General properties
Name, symbol	meitnerium, Mt
Pronunciation	/maɪtˈnɪəriəm/[1] or /ˈmaɪtnəriəm/[2] myt-NEER-ee-əm or MYT-nər-ee-əm
Meitnerium in the periodic table
Ir ↑ Mt ↓ (Uhu) hassium ← meitnerium → darmstadtium
Atomic number (Z)	109
Group, block	group 9, d-block
Period	period 7
Element category	unknown, but probably a transition metal[3][4]
Standard atomic weight (Ar)	[278]
Electron configuration	[Rn] 5f^14 6d^7 7s^2 (calculated)[3][5]
per shell	2, 8, 18, 32, 32, 15, 2 (predicted)
Physical properties
Phase	solid (predicted)[4]
Density near r.t.	37.4 g/cm^3 (predicted)[3]
Atomic properties
Oxidation states	9, 8, 6, 4, 3, 1 ​(predicted)[3][6][7][8]
Ionization energies	1st: 800.8 kJ/mol 2nd: 1823.6 kJ/mol 3rd: 2904.2 kJ/mol (more) (all estimated)[3]
Atomic radius	empirical: 128 pm (predicted)[3][8]
Covalent radius	129 pm (estimated)[9]
Miscellanea
Crystal structure	​face-centered cubic (fcc) (predicted)[4]
Magnetic ordering	paramagnetic (predicted)[10]
CAS Number	54038-01-6
History
Naming	after Lise Meitner
Discovery	Gesellschaft für Schwerionenforschung (1982)
Most stable isotopes of meitnerium
iso NA half-life DM DE (MeV) DP ^278Mt syn 7.6 s α 9.6 ^274Bh ^276Mt syn 0.72 s α 9.71 ^272Bh ^274Mt syn 0.44 s α 9.76 ^270Bh ^270mMt ? syn 1.1 s α ^266Bh

Meitnerium is a chemical element with symbol Mt and atomic number 109. It is an extremely radioactive synthetic element (an element not found in nature that can be created in a laboratory). The most stable known isotope, meitnerium-278, has a half-life of 7.6 seconds. The GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany, first created this element in 1982. It is named for Lise Meitner.

In the periodic table, meitnerium is a d-block transactinide element. It is a member of the 7th period and is placed in the group 9 elements, although no chemical experiments have been carried out to confirm that it behaves as the heavier homologue to iridium in group 9. Meitnerium is calculated to have similar properties to its lighter homologues, cobalt, rhodium, and iridium.

History

Meitnerium was named after the physicist Lise Meitner, one of the discoverers of nuclear fission.

Discovery

Meitnerium was first synthesized on August 29, 1982 by a German research team led by Peter Armbruster and Gottfried Münzenberg at the Institute for Heavy Ion Research (Gesellschaft für Schwerionenforschung) in Darmstadt.^[11] The team bombarded a target of bismuth-209 with accelerated nuclei of iron-58 and detected a single atom of the isotope meitnerium-266:

209
83Bi + 58
26Fe → 266
109Mt + n

Naming

Using Mendeleev's nomenclature for unnamed and undiscovered elements, meitnerium should be known as eka-iridium. In 1979, during the Transfermium Wars (but before the synthesis of meitnerium), IUPAC published recommendations according to which the element was to be called unnilennium (with the corresponding symbol of Une),^[12] a systematic element name as a placeholder, until the element was discovered (and the discovery then confirmed) and a permanent name was decided on. Although widely used in the chemical community on all levels, from chemistry classrooms to advanced textbooks, the recommendations were mostly ignored among scientists in the field, who either called it "element 109", with the symbol of (109) or even simply 109, or used the proposed name "meitnerium".^[3]

The naming of meitnerium was discussed in the element naming controversy regarding the names of elements 104 to 109, but meitnerium was the only proposal and thus was never disputed.^[13][14] The name meitnerium (Mt) was suggested in honor of the Austrian physicist Lise Meitner, a co-discoverer of protactinium (with Otto Hahn),^{[15][16][17][18][19]} and one of the discoverers of nuclear fission.^[20] In 1994 the name was recommended by IUPAC,^[13] and was officially adopted in 1997.^[14] It is thus the only element named specifically after a non-mythological woman (curium being named for both Pierre and Marie Curie).^[21]

Isotopes

List of meitnerium isotopes

Isotope	Half-life [22][23]	Decay mode[22][23]	Discovery year	Reaction
^265Mt	2? min	α ?	unknown	—
^266Mt	1.7 ms	α	1982	^209Bi(^58Fe,n)[11]
^267Mt	10? ms	α ?	unknown	—
^268Mt	21 ms	α	1994	^272Rg(—,α)[24]
^269Mt	0.2? s	α ?	unknown	—
^270Mt	5.0 ms	α	2004	^278Uut(—,2α)[25][26]
^271Mt	5? s	α ?	unknown	—
^272Mt	10? s	α, SF ?	unknown	—
^273Mt	20? s	α, SF ?	unknown	—
^274Mt	0.44 s	α, SF	2006	^282Uut(—,2α)[25]
^275Mt	9.7 ms	α	2003	^287Uup(—,3α)[25]
^276Mt	0.72 s	α, SF	2003	^288Uup(—,3α)[25]
^277Mt	~5 ms	SF	2012	^293Uus(—,4α)[27]
^278Mt	7.6 s	α	2009	^294Uus(—,4α)[28]
^279Mt	6? min	α, SF ?	unknown	—

Meitnerium has no stable or naturally-occurring isotopes. Several radioactive isotopes have been synthesized in the laboratory, either by fusing two atoms or by observing the decay of heavier elements. Eight different isotopes of meitnerium have been reported with atomic masses 266, 268, 270, and 274–278, two of which, meitnerium-268 and meitnerium-270, have known but unconfirmed metastable states. Most of these decay predominantly through alpha decay, although some undergo spontaneous fission.^[22]

Stability and half-lives

All meitnerium isotopes are extremely unstable and radioactive; in general, heavier isotopes are more stable than the lighter. The most stable known meitnerium isotope, ²⁷⁸Mt, is also the heaviest known; it has a half-life of 7.6 seconds. A metastable nuclear isomer, ^270mMt, has been reported to also have a half-life of over a second. The isotopes ²⁷⁶Mt and ²⁷⁴Mt have half-lives of 0.72 and 0.44 seconds respectively. The remaining four isotopes have half-lives between 1 and 20 milliseconds.^[22] The undiscovered isotope ²⁸¹Mt has been predicted to be the most stable towards beta decay;^[29] no known meitnerium isotope has been observed to undergo beta decay.^[22] Some unknown isotopes, such as ²⁶⁵Mt, ²⁷²Mt, ²⁷³Mt, and ²⁷⁹Mt, are predicted to have half-lives longer than the known isotopes.^[22][23] Before its discovery, ²⁷⁴Mt and ²⁷⁷Mt were predicted to have half-lives of 20 seconds and 1 minute respectively, but they were later found to have half-lives of only 0.44 seconds and 5 milliseconds respectively.^[22]

Predicted properties

Chemical

Meitnerium is the seventh member of the 6d series of transition metals. Since element 112 (copernicium) has been shown to be a transition metal, it is expected that all the elements from 104 to 112 would form a fourth transition metal series, with meitnerium as part of the platinum group metals.^[18] Calculations on its ionization potentials and atomic and ionic radii are similar to that of its lighter homologue iridium, thus implying that meitnerium's basic properties will resemble those of the other group 9 elements, cobalt, rhodium, and iridium.^[3]

Prediction of the probable chemical properties of meitnerium has not received much attention recently. Meitnerium is expected to be a noble metal. Based on the most stable oxidation states of the lighter group 9 elements, the most stable oxidation states of meitnerium are predicted to be the +6, +3, and +1 states, with the +3 state being the most stable in aqueous solutions. In comparison, rhodium and iridium show a maximum oxidation state of +6, while the most stable states are +4 and +3 for iridium and +3 for rhodium.^[3] The oxidation state +9, represented only by iridium in [IrO₄]⁺, might be possible for its congener meitnerium in the nonafluoride (MtF₉) and the [MtO₄]⁺ cation, although [IrO₄]⁺ is expected to be more stable.^[7] The tetrahalides of meitnerium have also been predicted to have similar stabilities to those of iridium, thus also allowing a stable +4 state.^[6] It is further expected that the maximum oxidation states of elements from bohrium (element 107) to darmstadtium (element 110) may be stable in the gas phase but not in aqueous solution.^[3]

Physical and atomic

Meitnerium is expected to be a solid under normal conditions and assume a face-centered cubic crystal structure, similarly to its lighter congener iridium.^[4] It should be a very heavy metal with a density of around 37.4 g/cm³, which would be the second-highest of any of the 118 known elements, second only to that predicted for its neighbor hassium (41 g/cm³). In comparison, the densest known element that has had its density measured, osmium, has a density of only 22.61 g/cm³. This results from meitnerium's high atomic weight, the lanthanide and actinide contractions, and relativistic effects, although production of enough meitnerium to measure this quantity would be impractical, and the sample would quickly decay.^[3] Meitnerium is also predicted to be paramagnetic.^[10]

Theoreticians have predicted the covalent radius of meitnerium to be 6 to 10 pm larger than that of iridium.^[30] For example, the Mt–O bond distance is expected to be around 1.9 Å.^[31] The atomic radius of meitnerium is expected to be around 128 pm.^[8]

Experimental chemistry

Unambiguous determination of the chemical characteristics of meitnerium has yet to have been established^[32][33] due to the short half-lives of meitnerium isotopes^[3] and a limited number of likely volatile compounds that could be studied on a very small scale. One of the few meitnerium compounds that are likely to be sufficiently volatile is meitnerium hexafluoride (MtF
6), as its lighter homologue iridium hexafluoride (IrF
6) is volatile above 60 °C and therefore the analogous compound of meitnerium might also be sufficiently volatile;^[18] a volatile octafluoride (MtF
8) might also be possible.^[3] For chemical studies to be carried out on a transactinide, at least four atoms must be produced, the half-life of the isotope used must be at least 1 second, and the rate of production must be at least one atom per week.^[18] Even though the half-life of ²⁷⁸Mt, the most stable known meitnerium isotope, is 7.6 seconds, long enough to perform chemical studies, another obstacle is the need to increase the rate of production of meitnerium isotopes and allow experiments to carry on for weeks or months so that statistically significant results can be obtained. Separation and detection must be carried out continuously to separate out the meitnerium isotopes and automated systems can then experiment on the gas-phase and solution chemistry of meitnerium as the yields for heavier elements are predicted to be smaller than those for lighter elements; some of the separation techniques used for bohrium and hassium could be reused. However, the experimental chemistry of meitnerium has not received as much attention as that of the heavier elements from copernicium to livermorium.^[3][32][34]

The Lawrence Berkeley National Laboratory attempted to synthesize the isotope ²⁷¹Mt in 2002–2003 for a possible chemical investigation of meitnerium because it was expected that it might be more stable than the isotopes around it as it has 162 neutrons, a magic number for deformed nuclei; its half-life was predicted to be a few seconds, long enough for a chemical investigation.^[3][35] However, no atoms of ²⁷¹Mt were detected,^[36] and this isotope of meitnerium is currently unknown.^[22]

An experiment determining the chemical properties of a transactinide would need to compare a compound of that transactinide with analogous compounds of some of its lighter homologues:^[3] for example, in the chemical characterization of hassium, hassium tetroxide (HsO₄) was compared with the analogous osmium compound, osmium tetroxide (OsO₄).^[37] In a preliminary step towards determining the chemical properties of meitnerium, the GSI attempted sublimation of the rhodium compounds rhodium(III) oxide (Rh₂O₃) and rhodium(III) chloride (RhCl₃). However, macroscopic amounts of the oxide would not sublimate until 1000 °C and the chloride would not until 780 °C, and then only in the presence of carbon aerosol particles: these temperatures are far too high for such procedures to be used on meitnerium, as most of the current methods used for the investigation of the chemistry of superheavy elements do not work above 500 °C.^[33]

References

1. Emsley, John (2003). Nature's Building Blocks. Oxford University Press. ISBN 978-0198503408. Retrieved 12 November 2012.
2. "Meitnerium". Periodic Table of Videos. The University of Nottingham. Retrieved 15 October 2012.
3. Hoffman, Darleane C.; Lee, Diana M.; Pershina, Valeria (2006). "Transactinides and the future elements". In Morss; Edelstein, Norman M.; Fuger, Jean. The Chemistry of the Actinide and Transactinide Elements (3rd ed.). Dordrecht, The Netherlands: Springer Science+Business Media. ISBN 1-4020-3555-1.
4. Östlin, A.; Vitos, L. (2011). "First-principles calculation of the structural stability of 6d transition metals". Physical Review B 84 (11). Bibcode:2011PhRvB..84k3104O. doi:10.1103/PhysRevB.84.113104.
5. Thierfelder, C.; Schwerdtfeger, P.; Heßberger, F. P.; Hofmann, S. (2008). "Dirac-Hartree-Fock studies of X-ray transitions in meitnerium". The European Physical Journal A 36 (2): 227. Bibcode:2008EPJA...36..227T. doi:10.1140/epja/i2008-10584-7.
6. Ionova, G. V.; Ionova, I. S.; Mikhalko, V. K.; Gerasimova, G. A.; Kostrubov, Yu. N.; Suraeva, N. I. (2004). "Halides of Tetravalent Transactinides (Rf, Db, Sg, Bh, Hs, Mt, 110th Element): Physicochemical Properties". Russian Journal of Coordination Chemistry 30 (5): 352. doi:10.1023/B:RUCO.0000026006.39497.82.
7. Himmel, Daniel; Knapp, Carsten; Patzschke, Michael; Riedel, Sebastian (2010). "How Far Can We Go? Quantum-Chemical Investigations of Oxidation State +IX". ChemPhysChem 11 (4): 865–9. doi:10.1002/cphc.200900910. PMID 20127784.
8. Fricke, Burkhard (1975). "Superheavy elements: a prediction of their chemical and physical properties". Recent Impact of Physics on Inorganic Chemistry 21: 89–144. doi:10.1007/BFb0116498. Retrieved 4 October 2013.
9. Chemical Data. Meitnerium - Mt, Royal Chemical Society
10. Saito, Shiro L. (2009). "Hartree–Fock–Roothaan energies and expectation values for the neutral atoms He to Uuo: The B-spline expansion method". Atomic Data and Nuclear Data Tables 95 (6): 836. Bibcode:2009ADNDT..95..836S. doi:10.1016/j.adt.2009.06.001.
11. Münzenberg, G.; Armbruster, P.; Heßberger, F. P.; Hofmann, S.; Poppensieker, K.; Reisdorf, W.; Schneider, J. H. R.; Schneider, W. F. W.; Schmidt, K.-H.; Sahm, C.-C.; Vermeulen, D. (1982). "Observation of one correlated α-decay in the reaction ⁵⁸Fe on ²⁰⁹Bi→²⁶⁷109". Zeitschrift für Physik A 309 (1): 89. Bibcode:1982ZPhyA.309...89M. doi:10.1007/BF01420157.
12. Chatt, J. (1979). "Recommendations for the naming of elements of atomic numbers greater than 100". Pure and Applied Chemistry 51 (2): 381–384. doi:10.1351/pac197951020381.
13. "Names and symbols of transfermium elements (IUPAC Recommendations 1994)". Pure and Applied Chemistry 66 (12): 2419. 1994. doi:10.1351/pac199466122419.
14. Rayner-Canham, Geoff; Zheng, Zheng (2007). "Naming elements after scientists: An account of a controversy". Foundations of Chemistry 10: 13. doi:10.1007/s10698-007-9042-1.
15. Bentzen, S. M. (2000). "Lise Meitner and Niels Bohr—a historical note". Acta oncologica (Stockholm, Sweden) 39 (8): 1002–1003. doi:10.1080/02841860050216016. PMID 11206992.
16. Kyle, R. A.; Shampo, M. A. (1981). "Lise Meitner". JAMA: the Journal of the American Medical Association 245 (20): 2021. doi:10.1001/jama.245.20.2021. PMID 7014939.
17. Frisch, O. R. (1973). "Distinguished Nuclear Pioneer—1973. Lise Meitner". Journal of nuclear medicine 14 (6): 365–371. PMID 4573793.
18. Griffith, W. P. (2008). "The Periodic Table and the Platinum Group Metals". Platinum Metals Review 52 (2): 114. doi:10.1595/147106708X297486.
19. Rife, Patricia (2003). "Meitnerium". Chemical & Engineering News 81 (36): 186. doi:10.1021/cen-v081n036.p186.
20. Wiesner, Emilie; Settle, Frank A. (2001). "Politics, Chemistry, and the Discovery of Nuclear Fission". Journal of Chemical Education 78 (7): 889. Bibcode:2001JChEd..78..889W. doi:10.1021/ed078p889.
21. "Meitnerium is named for the Austrian physicist Lise Meitner." in Meitnerium in Royal Society of Chemistry – Visual Element Periodic Table. Retrieved August 14, 2015.
22. Sonzogni, Alejandro. "Interactive Chart of Nuclides". National Nuclear Data Center: Brookhaven National Laboratory. Retrieved 2008-06-06.
23. Gray, Theodore (2002–2010). "The Photographic Periodic Table of the Elements". periodictable.com. Retrieved 16 November 2012.
24. Hofmann, S.; Ninov, V.; Heßberger, F. P.; Armbruster, P.; Folger, H.; Münzenberg, G.; Schött, H. J.; Popeko, A. G.; Yeremin, A. V.; Andreyev, A. N.; Saro, S.; Janik, R.; Leino, M. (1995). "The new element 111" (PDF). Zeitschrift für Physik A 350 (4): 281. Bibcode:1995ZPhyA.350..281H. doi:10.1007/BF01291182.
25. Oganessian, Yu. Ts.; Penionzhkevich, Yu. E.; Cherepanov, E. A. (2007). "Heaviest Nuclei Produced in 48Ca-induced Reactions (Synthesis and Decay Properties)". AIP Conference Proceedings 912: 235. doi:10.1063/1.2746600.
26. Morita, Kosuke; Morimoto, Kouji; Kaji, Daiya; Akiyama, Takahiro; Goto, Sin-ichi; Haba, Hiromitsu; Ideguchi, Eiji; Kanungo, Rituparna; Katori, Kenji; Koura, Hiroyuki; Kudo, Hisaaki; Ohnishi, Tetsuya; Ozawa, Akira; Suda, Toshimi; Sueki, Keisuke; Xu, HuShan; Yamaguchi, Takayuki; Yoneda, Akira; Yoshida, Atsushi; Zhao, YuLiang (2004). "Experiment on the Synthesis of Element 113 in the Reaction ²⁰⁹Bi(⁷⁰Zn,n)²⁷⁸113". Journal of the Physical Society of Japan 73 (10): 2593–2596. Bibcode:2004JPSJ...73.2593M. doi:10.1143/JPSJ.73.2593.
27. Oganessian, Yuri Ts.; Abdullin, F. Sh.; Alexander, C.; et al. (2013-05-30). "Experimental studies of the ²⁴⁹Bk + ⁴⁸Ca reaction including decay properties and excitation function for isotopes of element 117, and discovery of the new isotope ²⁷⁷Mt". Physical Review C (American Physical Society) 87 (054621). Bibcode:2013PhRvC..87e4621O. doi:10.1103/PhysRevC.87.054621.
28. Oganessian, Yuri Ts.; Abdullin, F. Sh.; Bailey, P. D.; et al. (2010-04-09). "Synthesis of a New Element with Atomic Number Z=117". Physical Review Letters (American Physical Society) 104 (142502). Bibcode:2010PhRvL.104n2502O. doi:10.1103/PhysRevLett.104.142502. PMID 20481935.
29. Nie, G. K. (2005). "Charge radii of β-stable nuclei". Modern Physics Letters A 21 (24): 1889. arXiv:nucl-th/0512023. Bibcode:2006MPLA...21.1889N. doi:10.1142/S0217732306020226.
30. Pyykkö, Pekka; Atsumi, Michiko (2009). "Molecular Double-Bond Covalent Radii for Elements Li—E112". Chemistry – A European Journal 15 (46): 12770. doi:10.1002/chem.200901472.
31. Van Lenthe, E.; Baerends, E. J. (2003). "Optimized Slater-type basis sets for the elements 1–118". Journal of Computational Chemistry 24 (9): 1142–56. doi:10.1002/jcc.10255. PMID 12759913.
32. Düllmann, Christoph E. (2012). "Superheavy elements at GSI: a broad research program with element 114 in the focus of physics and chemistry". Radiochimica Acta 100 (2): 67–74. doi:10.1524/ract.2011.1842.
33. Haenssler, F. L.; Düllmann, Ch. E.; Gäggeler, H. W.; Eichler, B. "Thermatographic investigation of Rh and ¹⁰⁷Rh with different carrier gases" (PDF). Retrieved 15 October 2012.
34. Eichler, Robert (2013). "First foot prints of chemistry on the shore of the Island of Superheavy Elements" (PDF). Journal of Physics: Conference Series (IOP Science) 420 (1). doi:10.1088/1742-6596/420/1/012003. Retrieved 11 September 2014.
35. Smolańczuk, R. (1997). "Properties of the hypothetical spherical superheavy nuclei". Phys. Rev. C 56 (2): 812–24. Bibcode:1997PhRvC..56..812S. doi:10.1103/PhysRevC.56.812.
36. Zielinski P. M. et al. (2003). "The search for ²⁷¹Mt via the reaction ²³⁸U + ³⁷Cl", GSI Annual report. Retrieved on 2008-03-01
37. Düllmann, Ch. E for a Univ. Bern - PSI - GSI - JINR - LBNL - Univ. Mainz - FZR - IMP - collaboration. "Chemical investigation of hassium (Hs, Z=108)" (PDF). Retrieved 15 October 2012.

External links

• Meitnerium at The Periodic Table of Videos (University of Nottingham)