Symbol	Pm
Atomnummer	61
Gruppe	-
Periode	6
Blok	f
Klassifikation	Lanthanider

Udseende	Metallic
Farve	Sølv

Antal protoner	61 p+
Antal neutroner	84 n0
Antal elektroner	61 e-

Fra Wikipedia, den gratis encyklopædiPromethium (opkaldt efter Prometheus fra den græske mytologi) er det 61. grundstof i det periodiske system, og har det kemiske symbol Pm: Det er et stærkt radioaktivt metal med kemiske egenskaber der ligner de øvrige lanthaniders. På grund af den stærke radioaktive stråling udsender salte af promethium et blegt blåt eller grønt lys. Rent, metallisk promethium har to allotrope former.

Fase ved STP	Fast
Massefylde	7.26 g/cm3
Atommasse	145 u

Smeltepunkt	1315 K 1041.85 °C 1907.33 °F
Kogepunkt	3273 K 2999.85 °C 5431.73 °F
Fordampningsvarme	289 kJ/mol

Elektronegativitet (Pauling Scale)	1.13
Elektronaffinitet	12.45 kJ/mol
Oxidationstrin	+2, +3 (a mildly basic oxide)
Ioniseringsenergier	540 kJ/mol 1050 kJ/mol 2150 kJ/mol 3970 kJ/mol

Elektronkonfiguration Kortfattet konfiguration	[Xe] 4f5 6s2
Elektronkonfiguration Fuld konfiguration	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f5 5s2 5p6 6s2
Elektronkonfigurationsdiagram	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f5 5s2 5p6 6s2
Elektroner pr. Skal	2, 8, 18, 23, 8, 2
Valenselektroner	2
Valency-elektroner	3
Bohrs atommodel	Figur: Skaldiagram af Promethium (Pm) atom.
Orbital diagram 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 6s

Opdaget	Charles D. Coryell, Jacob A. Marinsky, Lawrence E. Glendenin (1945)
Navngivet af	Grace Mary Coryell (1945)
Opdagelse af promethium In 1902 Bohuslav Brauner suggested that there was a then-unknown element with properties intermediate between those of the known elements neodymium (60) and samarium (62); this was confirmed in 1914 by Henry Moseley, who, having measured the atomic numbers of all the elements then known, found that atomic number 61 was missing. In 1926, two groups (one Italian and one American) claimed to have isolated a sample of element 61; both "discoveries" were soon proven to be false. In 1938, during a nuclear experiment conducted at Ohio State University, a few radioactive nuclides were produced that certainly were not radioisotopes of neodymium or samarium, but there was a lack of chemical proof that element 61 was produced, and the discovery was not generally recognized. Promethium was first produced and characterized at Oak Ridge National Laboratory in 1945 by the separation and analysis of the fission products of uranium fuel irradiated in a graphite reactor. The discoverers proposed the name "prometheum" (the spelling was subsequently changed), derived from Prometheus, the Titan in Greek mythology who stole fire from Mount Olympus and brought it down to humans, to symbolize "both the daring and the possible misuse of mankind's intellect". However, a sample of the metal was made only in 1963.

CAS Number	7440-12-2
ChemSpider ID	22386
EC number	231-121-9
PubChem CID Number	23944