Periodic Table of Elements
Element Protactinium - Pa
Comprehensive data on the chemical element Protactinium is provided on this page; including scores of properties, element names in many languages, most known nuclides of Protactinium. Common chemical compounds are also provided for many elements. In addition technical terms are linked to their definitions and the menu contains links to related articles that are a great aid in one's studies.
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Overview of Protactinium
- Atomic Number: 91
- Period: 7
- Series: Actinides
Protactinium's Name in Other Languages
- Latin: Protactinium
- Czech: Protaktinium
- Croatian: Protaktinij
- French: Protactinium
- German: Protaktinium - s
- Italian: Protoattinio
- Norwegian: Protactinium
- Portuguese: Protactínio
- Russian: Протактиний
- Spanish: Protactínio
- Swedish: Protaktinium
Atomic Structure of Protactinium
- Atomic Radius:
- Atomic Volume: 15cm3/mol
- Covalent Radius:
- Cross Section (Thermal Neutron Capture) σa/barns: 200.6
- Crystal Structure: Orthorhombic
- Electron Configuration:
- 1s2 2s2p6 3s2p6d10 4s2p6d10f14 5s2p6d10f2 6s2p6d1 7s2
- Electrons per Energy Level: 2,8,18,32,20,9,2
- Ionic Radius: 0.78Å
- Filling Orbital: 5f2
- Number of Electrons (with no charge): 91
- Number of Neutrons (most common/stable nuclide): 122
- Number of Protons: 91
- Oxidation States: 5,4
- Valence Electrons: 5f2 6d1 7s2
- Electron Dot Model
- Electron Dot Model
Chemical Properties of Protactinium
- Electrochemical Equivalent: 1.724g/amp-hr
- Electron Work Function:
- Electronegativity: 1.5 (Pauling); 1.014 (Allrod Rochow)
- Heat of Fusion: 12.3kJ/mol
- Incompatibilities:
- Ionization Potential
- First: 5.89
- Valence Electron Potential (-eV): 92
Physical Properties of Protactinium
- Atomic Mass Average: 213.0359
- Boiling Point: 4300K 4027°C 7281°F
- Coefficient of lineal thermal expansion/K-1: 7.3E-6
- Conductivity
- Electrical: 0.0529 106/cm Ω
Thermal: 0.47 W/cmK
- Electrical: 0.0529 106/cm Ω
- Density: 15.4g/cc @ 300K
- Description:
- Radioactive rare earth metal found naturally in uranium ores.
- Enthalpy of Fusion: 12.34 kJ/mole
- Flammablity Class:
- Freezing Point: see melting point
- Heat of Vaporization: kJ/mol
- Melting Point: 2113K 1600°C 2912°F
- Molar Volume: 15.03 cm3/mole
- Physical State (at 20°C & 1atm): Solid
- Specific Heat: 0.12J/gK
Regulatory / Health
- CAS Number
- 7440-13-3
- NFPA 704
- Health:
- Fire:
- Reactivity:
- Special Hazard: Radioactive<
- OSHA Permissible Exposure Limit (PEL)
- No limits set by OSHA
- OSHA PEL Vacated 1989
- No limits set by OSHA
- NIOSH Recommended Exposure Limit (REL)
- No limits set by NIOSH
- Levels In Humans:
Note: this data represents naturally occuring levels of elements in the typical human, it DOES NOT represent recommended daily allowances.- Blood/mg dm-3: nil
- Bone/p.p.m: nil
- Liver/p.p.m: nil
- Muscle/p.p.m: nil
- Daily Dietary Intake: nil
- Total Mass In Avg. 70kg human: nil
Who / Where / When / How
- Discoverer: Kasimir Fajans and O.H. Göhring
- Discovery Location: Karlsruhe Germany
- Discovery Year: 1913
- Name Origin:
- Greek: protos (first); its is the parent of actinium, which is formed by radioactive decay.
- Abundance of Protactinium:
- Earth's Crust/p.p.m.: N/A
- Seawater/p.p.m.: 2E-11
- Atmosphere/p.p.m.: N/A
- Sun (Relative to H=1E12): N/A
- Sources of Protactinium:
- Occurs in minute trace amounts in uranium ores such as pitchblende. Found among fission products of uranium, thorium, and plutonium. In 1961 the UK Atomic Energy Authority produced 125 g of pure protactinium from uranium fuel elements, which represents the major world stock of pratactinium.
- Uses of Protactinium:
- None
- Additional Notes:
- Different sources credit the discovery of Protactinium because Kasimir Fajans and O.H. Göhring discovered Pa-231 in 1913, while Lise Meitner and Otto Hahn (Germany), K. Fajans (Germany) and F. Soddy, J.A. Cranston and A. Fleck (Scotland) discovered Pa-231 in 1917. We suspect that geo-political rivalries surrounding the First World War resulted in the 1913 discovery being omitted from many sources.
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References
A list of reference sources used to compile the data provided on our periodic table of elements can be found on the main periodic table page.
Related Resources
- Anatomy of the Atom
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Introduces stoichiometry and explains the differences between molarity, molality and normality. - Molar Mass Calculations and Javascript Calculator
Molar mass calculations are explained and there is a JavaScript calculator to aid calculations. - Chemical Database
This database focuses on the most common chemical compounds used in the home and industry.
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