Protactinium: the essentials
Protactinium has a bright metallic lustre which it retains for some time in air. The element is superconductive below 1.4 K. The element is a dangerous toxic material and requires precautions similar to those used when handling plutonium. Protactinium is one of the rarest and most expensive naturally occurring elements. The element is an α-emitter and is a radiological hazard similar to polonium. Protactinium is a highly toxic and radioactive rare earth metal that requires special handling. It is found in pitchblende and ores form Zaire and is one of the rarest and most expensive naturally occurring elements.
This sample of uraninite contains some about 10-6 grammes of actinium at any one time. Image adapted with permission from Prof James Marshall's (U. North Texas, USA) Walking Tour of the elements CD.
Protactinium: historical information
Protactinium is found in pitchblende and ores form Zaire and is one of the rarest and most expensive naturally occurring elements. Protactinium was identified by Fajans and GΔhring in 1913 who named the new element brevium ("brief"). The metal itself was not isolated until 1934 when Aristid Grosse developed two methods. One involved reduction of the pentoxide Pa2O5 with a stream of electrons in a vacuum and the second involved heating the iodide PaI5 under vacuum.
Protactinium around us Read more »
Protactinium has no biological role.
Protactinium is found in pitchblende (uranite, UO2) and in ores from Zaire. It is present in such ores because it is a member of the 238U decay series. It is one of the rarest and most expensive naturally occurring elements.
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Physical properties Read more »
- Density of solid: 15370 kg m-3
- Molar volume: 15.18 cm3
- Thermal conductivity: 47 (estimate) W m‑1 K‑1
Heat properties Read more »
- Melting point: 1841 [1568 °C (2854 °F)] K
- Boiling point: 4300 [ca. 4000 °C (7232 °F)] K
- Enthalpy of fusion: 15 kJ mol-1
Crystal structure Read more »
The solid state structure of protactinium is: tetragonal.
Protactinium: orbital properties Read more »
Protactinium atoms have 91 electrons and the shell structure is 22.214.171.124.20.9.2. The ground state electronic configuration of neutral Protactinium is [Rn].5f2.6d1.7s2 and the term symbol of Protactinium is 4K11/2.
- Pauling electronegativity: 1.5 (Pauling units)
- First ionisation energy: 568 kJ mol‑1
- Second ionisation energy: (no data) kJ mol‑1
Isolation: coming soon!
Protactinium isotopes Read more »