Technetium, 43 Tc
General properties
Mass nummer
98 (most stable isotope)
Technetium in the periodic cairt
Atomic nummer (Z )
43
Group
group 7
Period
period 5
Element category
transition metal
Block
d-block
Electron confeeguration
[Kr ] 4d5 5s2
Electrons per shell
2, 8, 18, 13, 2
Pheesical properties
Phase (at STP )
solit
Meltin pynt
2430 K (2157 °C, 3915 °F)
Bylin pynt
4538 K (4265 °C, 7709 °F)
Density (near r.t. )
11 g/cm3
Heat o fusion
33.29 kJ/mol
Heat o vapourisation
585.2 kJ/mol
Molar heat capacity
24.27 J/(mol·K)
Vapour pressur (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
Pauling scale: 1.9
Atomic radius
empirical: 136 pm
Covalent radius
147±7 pm
Miscellanea
Creestal structur
hexagonal close-packed (hcp)
Speed o soond thin rod
16,200 m/s (at 20 °C)
Thermal conductivity
50.6 W/(m·K)
Magnetic orderin
Paramagnetic
CAS Nummer
7440-26-8
History
Predeection
Dmitri Mendeleev (1871)
Diskivery
Carlo Perrier an Emilio Segrè (1937)
First isolation
Carlo Perrier an Emilio Segrè (1937)
Main isotopes o technetium
| references | in Wikidata
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 isomer —technetium-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.