Protactinium melting point

Protactinium is a bright shiny metal. When exposed to air, it combines easily with oxygen to form a whitish coating of protactinium oxide. Its melting point is 2,840°F (1,560°C) and its density about 15.37 grams per cubic centimeter, more than 15 times the density of water. 

The influence of unoccupied 5/band states on the Fermi surface of thorium metal has been evaluated from precise calculations of the Fermi surface areas and effective masses.Comparison of the results with those obtained from experiments showed agreement when the 5/electrons were treated as itinerant. The nature of the bonding, electronic configurations and degree of localization of 5/ electrons in the actinide elements have been described in terms of a phenomenal model constructed from a knowledge of the crystal structure, the metallic radii, melting points and enthalpies of sublimation of the elements. The 5/electrons in the elements between protactinium... 

The production of uranium metal usually involves the reduction of UF4 with magnesium at 700°C. The metal may be refined by molten-salt electrolysis followed by zone melting. Because of the low melting point of uranium, the van Arkel process is not as feasible as for thorium and protactinium. 

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