Periodic Table/Protactinium
← ThU →
91Pa231.0359 Da

Protactinium

Actinide·Period 7·f-block

Radioactive metallic element, belongs to the actinoids. The most stable isotope, Pa-231 has a half-life of 2.43*10^4 years. At least 10 other radioactive isotopes are known. No practical applications are known. Discovered in 1917 by Lise Meitner and Otto Hahn.

Gallery

This sample of Protactinium-233 (dark circular area in the photo) was photographed in the light from its own radioactive emission (the lighter area) at the National Reactor Testing Station in Idaho.

ENERGY.GOV, Public domain, via Wikimedia Commons

Bohr model of Protactinium

Physical Propertiesmass · density · phase · crystal

Atomic Mass

231.0359Da

Density

15.4000g/cm³

Phase (STP)

Solid

Melting Point

1845.2K

Boiling Point

—

Molar Heat

—

Crystal Structure

TET

Lattice Constant

3.920Å

Atomic Radiiatomic · covalent · van der Waals

Atomic (Empirical)

180.00pm

Covalent

169.00pm

Van der Waals

243.00pm

Electronic Propertieselectronegativity · ionization · affinity

Electron Configuration

[Rn] 5f2 6d 7s2

Electron Shells

2, 8, 18, 32, 20, 9, 2

Electronegativity

1.50Pauling

Electron Affinity

—

1st Ionization Energy

5.9kJ/mol

Oxidation States

+3, +4, +5

Orbital DiagramAufbau · Hund's rule · Pauli exclusion

↑↓
1s2
↑↓
2s2
↑↓
↑↓
↑↓
2p6
↑↓
3s2
↑↓
↑↓
↑↓
3p6
↑↓
↑↓
↑↓
↑↓
↑↓
3d10
↑↓
4s2
↑↓
↑↓
↑↓
4p6
↑↓
↑↓
↑↓
↑↓
↑↓
4d10
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
4f14
↑↓
5s2
↑↓
↑↓
↑↓
5p6
↑↓
↑↓
↑↓
↑↓
↑↓
5d10
↑↓
6s2
↑↓
↑↓
↑↓
6p6
↑
↑
5f2
↑
6d1
↑↓
7s2

Full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 5f2 6d1 7s2Short: [Rn] 5f2 6d 7s2

Ionization Energies (91 known)

1st5.9 kJ/mol2nd11.9 kJ/mol3rd18.6 kJ/mol4th30.9 kJ/mol5th44.3 kJ/mol6th72.0 kJ/mol7th85.1 kJ/mol8th98.9 kJ/mol9th111.0 kJ/mol10th137.0 kJ/mol11th153.0 kJ/mol12th187.0 kJ/mol13th203.0 kJ/mol14th292.0 kJ/mol15th316.0 kJ/mol16th342.0 kJ/mol17th369.0 kJ/mol18th395.0 kJ/mol19th423.0 kJ/mol20th460.0 kJ/mol21th488.0 kJ/mol22th518.0 kJ/mol23th546.0 kJ/mol24th690.0 kJ/mol25th720.0 kJ/mol26th760.0 kJ/mol27th790.0 kJ/mol28th880.0 kJ/mol29th920.0 kJ/mol30th1020.0 kJ/mol31th1060.0 kJ/mol32th1150.0 kJ/mol33th1220.0 kJ/mol34th1300.0 kJ/mol35th1370.0 kJ/mol36th1450.0 kJ/mol37th1520.0 kJ/mol38th1600.0 kJ/mol39th1670.0 kJ/mol40th1760.0 kJ/mol41th1830.0 kJ/mol42th1910.0 kJ/mol43th1980.0 kJ/mol44th2060.0 kJ/mol45th2130.0 kJ/mol46th2483.0 kJ/mol47th2550.0 kJ/mol48th2620.0 kJ/mol49th2696.0 kJ/mol50th2766.0 kJ/mol51th2837.0 kJ/mol52th2968.0 kJ/mol53th3040.0 kJ/mol54th3119.0 kJ/mol55th3193.0 kJ/mol56th3488.0 kJ/mol57th3558.0 kJ/mol58th3637.0 kJ/mol59th3709.0 kJ/mol60th4077.0 kJ/mol61th4161.0 kJ/mol62th4370.0 kJ/mol63th4454.0 kJ/mol64th7181.0 kJ/mol65th7341.0 kJ/mol66th7510.0 kJ/mol67th7690.0 kJ/mol68th7870.0 kJ/mol69th8040.0 kJ/mol70th8410.0 kJ/mol71th8590.0 kJ/mol72th8780.0 kJ/mol73th8960.0 kJ/mol74th9460.0 kJ/mol75th9620.0 kJ/mol76th9790.0 kJ/mol77th9950.0 kJ/mol78th11100.0 kJ/mol79th11290.0 kJ/mol80th11660.0 kJ/mol81th11840.0 kJ/mol82th24660.0 kJ/mol83th25080.0 kJ/mol84th25540.0 kJ/mol85th25970.0 kJ/mol86th30230.0 kJ/mol87th30800.0 kJ/mol88th31520.0 kJ/mol89th31971.6 kJ/mol90th126304.8 kJ/mol91th128507.0 kJ/molSuccessive Ionization Energies

Emission Spectrumvisible range · characteristic spectral lines

389
442
Pa emission
380nm750nm
389.1 nm(100%)442.0 nm(40%)

Abundanceby mass

🌍Earth's Crust
1.4 ppt
🌊Ocean
5.0e-11 ppm
✨Universe—
🧬Human Body—

Log scale · ppm = parts per million by mass

Biological Role

Toxic

Radioactive and toxic. No biological role.

Discovery

Discovered By

Fredrich Soddy, John Cranston, Otto Hahn, Lise Meitner

Named By

—

Year

1917

Nuclear Data

Known Isotopes

31

Stable Isotopes

0

Stable Mass Numbers

None

Natural isotopic abundance (IUPAC recommended values)

Isotopes of Pa31 known

NuclideZNMass (AMU)Half-lifeDecayJπAbundance
211Pa91120211.0236746.00 msα (1%), β⁺, p9/2-—
212Pa91121212.0231855.80 msα (1%)3+—
213Pa91122213.0211007.40 msα (1%)9/2-—
231Pa91140231.03588332.6 kyα (1%), SF (0.03%), 24Ne (0.134%), 23F (0.099%)3/2-10000.0000%
239Pa91148239.0572601.80 hβ⁻ (1%)1/2+—
240Pa91149240.061203Unknownβ⁻3+—
241Pa91150241.064134Unknownβ⁻1/2+—

Click any isotope for its full page with decay chain:

211Pa212Pa213Pa214Pa215Pa216Pa217Pa218Pa219Pa220Pa221Pa222Pa223Pa224Pa225Pa226Pa227Pa228Pa229Pa230Pa231Pa232Pa233Pa234Pa235Pa236Pa237Pa238Pa239Pa240Pa241Pa
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