PaZ =  91

From the Greek "protos + aktis", meaning "first beam element"
(AM) Atomic Mass 231.0359  amu    Oxidation States +4, +5
   (BP) Boiling Point n/a    (MP) Melting Point 1600  °C
   (ρ) Density n/a    Crystal Structure Tetragonal
   ( χ ) Electronegativity 1.5    (AR) Atomic Radius n/a
   Physical State Solid (C) Heat Capacity n/a
Electronic-Config [Rn]  5f2  6d1  7s2     (I1) First Ionization E 568.3  kJ/mol
   (ΔHvap) Heat of Vaporization 481  kJ/mol     (ΔHfus) Heat of Fusion 12.34  kJ/mol
   Year of Discovery 1913    Location of Discovery United Kingdom
(E°) Standard Potential Pa4+⇔ Pa3+ (-1.900 V)
Stable isotopes None. All natural isotopes are radioactive
Discovered/Synthesized by Kasimir Fajans, O.H. Göhring
Natural Source Isolated from the decay of Uranium
Common Uses Scientific study
Other Info One of the rarest and most expensive naturally occurring elements
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