Promethium

Radioactive element
Latin namePromethium
English namePromethium
chemical symbolPm
atomic number61
relative atomic mass(144,9127)
period6
groupIII.B
classificationlanthanides
discovery year1945
discovererMarinsky, Glendenin
Coryell
melting point [°C]1042
boiling point [°C]3000
density [g cm-3]6,475
electronegativity [Pauling]1,13
oxidation statesIII
electron configuration[Xe]4f5 6s2
atomic radius [pm]205
specific heat [J g-1K-1]0,18
heat of fusion [kJ mol-1]7,7
thermal conductivity [W m-1 K-1]15
el. conductivity [S m-1]1,3.106
1. ionizing potential [eV]5,55
2. ionizing potential [eV]10,903
3. ionizing potential [eV]22,283
shear modulus [GPa]18
Young's modulus [GPa]46
state at normal conditionssolid

Promethium is an artificial radioactive metallic element. Does not occur in nature and has no practical use.

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