Technetium

Symbol	Tc
Atomnummer	43
Gruppe	7 (Mangangruppe)
Periode	5
Blok	d
Klassifikation	Overgangsmetal

Udseende	Shiny gray metal
Farve	Sølv

Antal protoner	43 p+
Antal neutroner	55 n0
Antal elektroner	43 e-

Fra Wikipedia, den gratis encyklopædiTechnetium er et grundstof med kemisk symbol Tc og atomnummer 43 i det periodiske system. Det tilhører gruppen af overgangsmetaller. Technetium har det laveste atomnummer af alle stofferne uden stabile isotoper i det periodiske system. Stort set alt technetium er fremstillet ad kunstig vej, og i naturen forefindes kun spormængder af grundstoffet. Technetium forekommer naturligt som et spontant fissionsprodukt i uranmalme og som resultat af neutronindfangning i molybdænmalme. Under normale temperatur- og trykforhold optræder technetium som et radioaktivt sølvgråt metal, der minder om platin. Dets kemiske egenskaber kan betragtes som en mellemting mellem rheniums og mangans.

Fase ved STP	Fast
Massefylde	11 g/cm3
Atommasse	98.9062 u

Smeltepunkt	2430 K 2156.85 °C 3914.33 °F
Kogepunkt	4538 K 4264.85 °C 7708.73 °F
Fordampningsvarme	502 kJ/mol

Elektronegativitet (Pauling Scale)	1.9
Elektronaffinitet	53 kJ/mol
Oxidationstrin	−3, −1, 0, +1, +2, +3, +4, +5, +6, +7 (a strongly acidic oxide)
Ioniseringsenergier	702 kJ/mol 1470 kJ/mol 2850 kJ/mol

Elektronkonfiguration Kortfattet konfiguration	[Kr] 4d5 5s2
Elektronkonfiguration Fuld konfiguration	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d5 5s2
Elektronkonfigurationsdiagram	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d5 5s2
Elektroner pr. Skal	2, 8, 18, 13, 2
Outer shell electrons	2
Valence electrons (incl. d)	7
Valency-elektroner	4
Bohrs atommodel	Figur: Skaldiagram af Technetium (Tc) atom.
Orbital diagram	1s 2s 2p 3s 3p 3d 4s 4p 4d 5s

Forudsigelse	Dmitri Mendeleev (1871)
Opdagelse og første isolation	Carlo Perrier, Emilio Segrè (1937)
Opdagelse af technetium From the 1860s through 1871, early forms of the periodic table proposed by Dmitri Mendeleev contained a gap between molybdenum (element 42) and ruthenium (element 44). In 1871, Mendeleev predicted this missing element would occupy the empty place below manganese and have similar chemical properties. The discovery of element 43 was finally confirmed in a 1937 experiment at the University of Palermo in Sicily by Carlo Perrier and Emilio Segrè. Segrè enlisted his colleague Perrier to attempt to prove, through comparative chemistry, that the molybdenum activity was indeed from an element with the atomic number 43. In 1937, they succeeded in isolating the isotopes technetium-95m and technetium-97. University of Palermo officials wanted them to name their discovery "panormium", after the Latin name for Palermo, Panormus. In 1947 element 43 was named after the Greek word τεχνητός, meaning "artificial", since it was the first element to be artificially produced.

Original word	technetos
Language of origin	Greek
Name source	Egenskaber
Meaning	“Artificial”
Naming The name is derived from the Greek word 'tekhnetos' meaning artificial, because it was the first manmade element synthesized.

CAS Number	7440-26-8
ChemSpider ID	22396
EC number	231-136-0
PubChem CID Number	23957