Chemicool

Pa

91

231.0359
Protactinium
General | States | Energies | Oxidation & Electrons |Appearance & Characteristics
Reactions | Other Forms |Radius | Conductivity | Abundance
Encyclopedia Britannica articles

General

Name Protactinium Symbol Pa
atomic number 91 Atomic weight 231.0359
Density @ 293 K 15.4 g/cm3 Atomic volume 15.0 cm3/mol
Group Rare Earth, Actinides discovered 1917

States

state (s, l, g) s
melting point 1873.2 K boiling point 4500 K
Heat of fusion 12.30 kJ/mol Heat of vaporization ?
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Energies

1st ionization energy 568 kJ/mole electronegativity 1.5
2nd ionization energy kJ/mole electron affinity kJ/mole
3rd ionization energy kJ/mole Specific heat 0.12 J/gK
heat atomization 527 kJ/mole atoms

Oxidation & Electrons

Shells 2,8,18,32,20,9,2 electron configuration [Rn] 5f2 6d1 7s2
minimum oxidation number 0 maximum oxidation number 5
min. common oxidation no. 0 max. common oxidation no. 5
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Appearance & Characteristics

structure fcc: face-centered cubic color silvery
uses toxicity
hardness mohs characteristics Radioactive

Reactions

reaction with air reaction with 6M HCl
reaction with 6M HCl reaction with 15M HNO3
reaction with 6M NaOH none
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Other Forms

number of isotopes 1 hydride(s) PaH3
oxide(s) PaO PaO2 Pa2O5 chloride(s) PaCl4 PaCl5

Radius

ionic radius (2- ion) pm ionic radius (1- ion) pm
atomic radius 163 pm ionic radius (1+ ion) pm
ionic radius (2+ ion) pm ionic radius (3+ ion) 118 pm
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Conductivity

thermal conductivity J/m-sec-deg electrical conductivity 1/mohm-cm
polarizability 25.4 A^3

Abundance

source Synthetic(U-235 decay) rel. abund. solar system log
abundance earth's crust -5.9 log cost, pure $/100g
cost, bulk $/100g
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