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Encyclopedia > Meitnerium
 109 hassium ← meitnerium → darmstadtium Ir ↑ Mt ↓ (Upe)
General
Name, Symbol, Number meitnerium, Mt, 109
Chemical series transition metals
Group, Period, Block 9, 7, d
Appearance unknown, probably silvery
white or metallic gray
Standard atomic weight [276] g·mol−1
Electron configuration perhaps [Rn] 5f14 6d7 7s2
(guess based on iridium)
Electrons per shell 2, 8, 18, 32, 32, 15, 2
Phase presumably a solid
CAS registry number 54038-01-6
Selected isotopes
Main article: Isotopes of meitnerium
iso NA half-life DM DE (MeV) DP
276Mt syn 0.72 s α 9.71 272Bh
275Mt syn 9.7 ms α 10.33 271Bh
274Mt syn 0.44 s α 9.76 270Bh
270mMt ? syn 1.1 s α 266Bh
270gMt syn 5 ms α 10.03 266Bh
268Mt syn 42 ms α 10.26,10.10 264Bh
266Mt syn 1.7 ms α 11.00 262Bh
References

Meitnerium

Common English pronunciation of meitnerium
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Mt is a synthetic element whose most stable isotope, Mt-278, has a predicted half-life of a half-hour. The chemical elements labelled as synthetic are unstable, with a half-life so short (ranging from a fraction of millisecond to a few million years) relative to the age of the Earth that any atoms of that element that may have been present when the Earth formed have long since... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ...

## Discovery profile

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.[1] The team bombarded a target of bismuth-209 with accelerated nuclei of iron-58 and detected a single atom of the isotope meitnerium-266: This article or section should be merged with Timeline of chemical element discovery The story of the discoveries of the chemical elements is presented here in chronological order. ... is the 241st day of the year (242nd in leap years) in the Gregorian calendar. ... Year 1982 (MCMLXXXII) was a common year starting on Friday (link displays the 1982 Gregorian calendar). ... Peter Armbruster (born July 25 1931 in Dachau, Bavaria) is a physicist at the Gesellschaft fÃ¼r Schwerionenforschung (GSI) facility in Darmstadt, Germany, and is credited with discovering elements 108 Hassium, 109 Meitnerium, 110 (darmstadtium), 111 (roentgenium), and 112 (ununbium). ... Gottfried MÃ¼nzenberg (born 1940 in Nordhausen, Germany) is a German physicist. ... The Gesellschaft fÃ¼r Schwerionenforschung mbH (GSI, Institute for Heavy Ion Research) in Wixhausen, a suburb of Darmstadt, Germany is a federally funded heavy ion research center. ... For other uses, see Darmstadt (disambiguation). ... General Name, Symbol, Number bismuth, Bi, 83 Chemical series poor metals Group, Period, Block 15, 6, p Appearance lustrous pink Standard atomic weight 208. ... Fe redirects here. ... For other uses, see Isotope (disambiguation). ...

$, ^{209}_{83}mathrm{Bi} + , ^{58}_{26}mathrm{Fe} , to , ^{266}_{109}mathrm{Mt} + , ^{1}_{0}mathrm{n}$

## Proposed names

Historically, element 109 has been referred to as eka-iridium. Professor Dimitri Mendeleev published the first Periodic Table of the Atomic Elements in 1869 based on properties which appeared with some regularity as he laid out the elements from lightest to heaviest. ... This article is about the chemical element. ...

The name meitnerium (Mt) was suggested in honor of the Austrian physicist and mathematician Lise Meitner, but there was an element naming controversy as to what the elements from 101 to 109 were to be called; thus IUPAC adopted unnilennium (/ˌjuːnɪˈlɛniəm/[2] or /ˌʌːnɪˈlɛniəm/, symbol Une) as a temporary, systematic element name. In 1997, however, the dispute was resolved and the current name was adopted. Lise Meitner ca. ... The names for the chemical elements 104 to 109 were the subject of a major controversy starting in the 1960s which was finally resolved in 1997. ... The International Union of Pure and Applied Chemistry (IUPAC) is an international non-governmental organization devoted to the advancement of chemistry. ... In chemistry, heavy transuranic elements receive a permanent trivial name and symbol only after their synthesis has been confirmed. ... For the band, see 1997 (band). ...

## Electronic structure

Meitnerium is element 109 in the Periodic Table. The two forms of the projected electronic structure are:

Bohr model: 2, 8, 18, 32, 32, 15, 2

Quantum mechanical model: 1s22s22p63s23p64s23d10 4p65s24d105p66s24f145d10 6p67s25f146d7

## Extrapolated chemical properties of meitnerium

### Oxidation states

Meitnerium is projected to be the sixth member of the 6d series of transition metals and the heaviest member of group 9 in the Periodic Table, below cobalt, rhodium and iridium. This group of transition metals is the first to show lower oxidation states and the +IX state is not known. The latter two members of the group show a maximum oxidation state of +VI, whilst the most stable states are +IV and +III for iridium and +III for rhodium. Meitnerium is therefore expected to form a stable +III state but may also portray stable +IV and +VI states. For other uses, see Cobalt (disambiguation). ... General Name, Symbol, Number rhodium, Rh, 45 Chemical series transition metals Group, Period, Block 9, 5, d Appearance silvery white metallic Standard atomic weight 102. ... This article is about the chemical element. ... In chemistry, the term transition metal (sometimes also called a transition element) has two possible meanings: It commonly refers to any element in the d-block of the periodic table, including zinc, cadmium and mercury. ...

### Chemistry

The +VI state is known only for the fluorides which are formed by direct reaction. Therefore, meitnerium should form a hexafluoride, MtF6. This fluoride is expected to be more stable than iridium(VI) fluoride, as the +VI state becomes more stable as the group is descended. In combination with oxygen, rhodium forms Rh2O3 whilst iridium is oxidised to the +IV state in IrO2. Meitnerium may therefore show a dioxide MtO2 if eka-iridium reactivity is shown. The +III state is common in the trihalides (not fluorides) formed by direct reaction with halogens. Meitnerium should therefore form MtCl3, MtBr3 and MtI3 in an analogous manner to iridium. This article is about the chemical series. ...

## History of synthesis of isotopes in cold fusion

### 209Bi(58Fe,xn)267-xMt (x=1)

The first success in this reaction was in 1982 by the GSI team in their discovery experiment with the identification of a single atom of 266Mt in the 1n neutron evaporation channel.[1] The GSI team used the parent-daughter correlation technique. After an initial failure in 1983, in 1985 the team at the FLNR, Dubna, observed alpha decays from the descendant 246Cf indicating the formation of meitnerium. The GSI synthesised a further 2 atoms of 266Mt in 1988 and continued in 1997 with the detection of 12 atoms during the measurement of the 1n excitation function. [3] [4] GSI may refer to: Geological Survey of India Geological Survey of Iran Geophysical Service Incorporated, petroleum exploration corporation Gesellschaft fÃ¼r Schwerionenforschung, ion research laboratory Gemological Science International GSI Outdoors, outdoors cookware company Grid Security Infrastructure Government Secure Intranet, the system for managing secure access to e-mail and other...

### 208Pb(59Co,xn)267-xMt (x=1)

This reaction was first studied in 1985 by the team in Dubna. They were able to detect the alpha decay of the descendant 246Cf nuclei indicating the formation of meitnerium atoms. In 2007, in a continuation of their study of the effect of odd-Z projectiles on yields of evaporation residues in cold fusion reactions, the team at LBNL synthesised 266Mt and were able to correlate the decay with known daughters.

### 181Ta(86Kr,xn)267-xMt

There are indications that this cold fusion reaction using a tantalum target was attempted in August 2001 at the GSI. No details can be found suggesting that no atoms of meitnerium were detected. General Name, Symbol, Number tantalum, Ta, 73 Chemical series transition metals Group, Period, Block 5, 6, d Appearance gray blue Standard atomic weight 180. ...

## History of synthesis by hot fusion reactions

### 238U(37Cl,xn)275-xMt

In 2002-2003, the team at LBNL attempted the above reaction in order to search for the isotope 271Mt with hope that it may be sufficiently stable to allow a first study of the chemical properties of meitnerium. Unfortunately, no atoms were detected and a cross section limit of 1.5 pb was measured for the 4n channel at the projectile energy used. [5]

### 254Es(22Ne,xn)276-xMt

Attempts to produce long-living isotopes of meitnerium were first performed by Ken Hulet at the Lawrence Livermore National Laboratory (LLNL) in 1988 using the asymmetric hot fusion reaction above. They were unable to detect any product atoms and established a cross section limit of 1 nb.[6]

## Synthesis of isotopes as decay products

Isotopes of meitnerium have also been detected in the decay of heavier elements. Observations to date are shown in the table below:

Evaporation Residue Observed Mt isotope
288115 276Mt
287115 275Mt
282113 274Mt
278113 270Mt
272Rg 268Mt

## Chronology of isotope discovery

Isotope Year discovered discovery reaction
266Mt 1982 209Bi(58Fe,n)[1]
267Mt unknown
268Mt 1994 209Bi(64Ni,n)[7]
269Mt unknown
270Mt 2004 209Bi(70Zn,n)[8]
271Mt unknown
272Mt unknown
273Mt unknown
274Mt 2006 237Np(48Ca,3n)[8]
275Mt 2003 243Am(48Ca,4n)[9]
276Mt 2003 243Am(48Ca,3n)[9]

## Chemical yields of isotopes

### Cold Fusion

The table below provides cross-sections and excitation energies for cold fusion reactions producing meitnerium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel.

Projectile Target CN 1n 2n 3n
58Fe 209Bi 267Mt 7.5 pb
59Co 208Pb 267Mt 2.6 pb , 14.9 MeV

## Isomerism in meitnerium nuclides

### 270Mt

Two atoms of 270Mt have been identified in the decay chains of 278113. The two decays have very different lifetimes and decay energiesand are also produced from two apparently different isomers in 274Rg. The first isomer decays by emission of an 10.03 MeV alpha particle with a lifetime 7.2 ms. The other decays by emitting an alpha particle with a lifetime of 1.63 s. An assignment to specific levels is not possible with the limited data available. Further research is required.

### 268Mt

The alpha decay spectrum for 268Mt appears to be complicated from the results of several experiments. Alpha lines of 10.28,10.22 ans 10.10 MeV have been observed. Half-lives of 42 ms, 21 ms and 102 ms have been determined. The long-lived decay is associated with alpha particles of energy 10.10 MeV and must be assigned to an isomeric level. The discrepancy between the other two half-lives has yet to be resolved. An assignment to specific levels is not possible with the data available and further research is required.

## References

1. ^ a b c "Observation of one correlated α-decay in the reaction 58Fe on 209Bi→267109", Munzenberg et al., Z. Phys. A., 1982, 309, 1. Retrieved on 2008-03-01
2. ^ unnilennium - Definitions from Dictionary.com
3. ^ "New results on element 109", Munzenberg et al., Z. Phys. A., 1988, 330, 4. Retrieved on 2008-03-01
4. ^ "Excitation function for the production of 265108 and 266109", Hofmann et al., Z. Phys. A., 1997, 358, 4. Retrieved on 2008-03-01
5. ^ "The search for 271Mt via the reaction 238U + 37Cl", Zielinski et al., GSI Annual report, 2003. Retrieved on 2008-03-01
6. ^ see reference 4 for reference to an internal report from LLNL
7. ^ see roentgenium for details
8. ^ a b see ununtrium for details
9. ^ a b see ununpentium for details

2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Common Era (or Anno Domini), in accordance with the Gregorian calendar. ... is the 60th day of the year (61st in leap years) in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Common Era (or Anno Domini), in accordance with the Gregorian calendar. ... is the 60th day of the year (61st in leap years) in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Common Era (or Anno Domini), in accordance with the Gregorian calendar. ... is the 60th day of the year (61st in leap years) in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Common Era (or Anno Domini), in accordance with the Gregorian calendar. ... is the 60th day of the year (61st in leap years) in the Gregorian calendar. ... General Name, Symbol, Number roentgenium, Rg, 111 Chemical series transition metals Group, Period, Block 11, 7, d Appearance unknown, probably yellow or orange metallic Atomic mass (284) g/mol Electron configuration perhaps [Rn] 5f14 6d10 7s1 (guess based on gold) Electrons per shell 2, 8, 18, 32, 32, 18, 1... General Name, Symbol, Number ununtrium, Uut, 113 Chemical series presumably poor metals Group, Period, Block 13, 7, p Appearance unknown, probably silvery white or metallic gray Atomic mass (284) g/mol Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p1 (guess based on thallium) Electrons per shell 2, 8, 18, 32... General Name, Symbol, Number ununpentium, Uup, 115 Group, Period, Block 15, 7, p Atomic mass (299) gÂ·molâˆ’1 Electron configuration perhaps [Rn] 5f14 6d10 7s2 7p3 (guess based on bismuth) Electrons per shell 2, 8, 18, 32, 32, 18, 5 CAS registry number 54085-64-2 Selected isotopes References...

Results from FactBites:

 WebElements Periodic Table of the Elements | Meitnerium | Essential information (404 words) Brief description: element 109, meitnerium, is a synthetic element that is not present in the environment at all. Isolation of an observable quantity of meitnerium has never been achieved, and may well never be. This is because meitnerium decays very rapidly through the emission of α-particles.
 Meitnerium (Mt) - Chemical properties, Health and Environmental effects (142 words) None of meitnerium's chemistry has been researched, but it should resemble other elements of group 9, like iridium. Meitnerium does not have any known application and little is known about it. Meitnerium is not found free in the environment, since it is a synthetic element.
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