Technetium

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Technetium
43Tc
Mn

Tc

Re
molybdenumtechnetiumruthenium
General properties
Name, seembol, nummer technetium, Tc, 43
Pronunciation /tɛkˈnʃiəm/
tek-NEE-shee-əm
Element category transeetion metal
Group, period, block 7, 5, d
Staundart atomic wicht [98]
Electron confeeguration [Kr] 4d5 5s2
2, 8, 18, 13, 2
Electron shells of technetium (2, 8, 18, 13, 2)
History
Prediction Dmitri Mendeleev (1871)
Discovery Carlo Perrier an Emilio Segrè (1937)
First isolation Carlo Perrier an Emilio Segrè (1937)
Physical properties
Phase solid
Density (near r.t.) 11 g·cm−3
Meltin pynt 2430 K, 2157 °C, 3915 °F
Boilin pynt 4538 K, 4265 °C, 7709 °F
Heat o fusion 33.29 kJ·mol−1
Heat o vaporization 585.2 kJ·mol−1
Molar heat capacity 24.27 J·mol−1·K−1
Vapor pressure (extrapolatit)
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 2727 2998 3324 3726 4234 4894
Atomic properties
Oxidation states 7, 6, 5, 4, 3[1], 2, 1[2], -1, -3
(strangly acidic oxide)
Electronegativity 1.9 (Pauling scale)
Ionization energies 1st: 702 kJ·mol−1
2nd: 1470 kJ·mol−1
3rd: 2850 kJ·mol−1
Atomic radius 136 pm
Covalent radius 147±7 pm
Miscellanea
Crystal structure hexagonal close-packed
Technetium has a hexagonal close packed crystal structure
Magnetic orderin Paramagnetic
Thermal conductivity 50.6 W·m−1·K−1
Speed of sound (thin rod) (20 °C) 16,200 m·s−1
CAS registry nummer 7440-26-8
Most stable isotopes
Main article: Isotopes o technetium
iso NA hauf-life DM DE (MeV) DP
95mTc syn 61 d ε - 95Mo
γ 0.204, 0.582,
0.835
-
IT 0.0389, e 95Tc
96Tc syn 4.3 d ε - 96Mo
γ 0.778, 0.849,
0.812
-
97Tc syn 2.6×106 y ε - 97Mo
97mTc syn 91 d IT 0.965, e 97Tc
98Tc syn 4.2×106 y β 0.4 98Ru
γ 0.745, 0.652 -
99Tc trace 2.111×105 y β 0.294 99Ru
99mTc syn 6.01 h IT 0.142, 0.002 99Tc
γ 0.140 -
· r

Technetium is the chemical element wi atomic number 43 an seembol Tc. It is the lawest atomic number element wioot ony stable isotopes; every fairm o it is radioactive. Nearly aw technetium is produced synthetically, an anly minute amoonts are foond in naitur. Naiturally occurrin technetium occurs as a spontaneous fission product in uranium ore or bi neutron capture in molybdenum ores. The chemical properties o this sillery gray, crystalline transeetion metal are intermediate atween rhenium an manganese.

Mony o technetium's properties wur predictit bi Dmitri Mendeleev afore the element wis discovered. Mendeleev notit a gap in his periodic table an gae the undiscovered element the provisional name ekamanganese (Em). In 1937, technetium (specifically the technetium-97 isotope) acame the first predominantly airtificial element tae be produced, hence its name (frae the Greek τεχνητός, meanin "airtificial").

Its short-lived gamma ray-emitting nuclear isomertechnetium-99m—is uised in nuclear medicine for a wide variety o diagnostic tests. Technetium-99 is uised as a gamma ray-free soorce o beta pairticles. Lang-lived technetium isotopes produced commercially are bi-products o fission o uranium-235 in nuclear reactors an are extractit frae nuclear fuel rods. Acause na isotope o technetium haes a hauf-life langer than 4.2 million years (technetium-98), its detection in 1952 in red giants, which are billions o years auld, helped bolster the theory that starns can produce hivier elements.

References[eedit | eedit soorce]

  1. "Technetium: technetium(III) iodide compound data". OpenMOPAC.net. Retrieved 2007-12-10. 
  2. "Technetium: technetium(I) fluoride compound data". OpenMOPAC.net. Retrieved 2007-12-10.