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Table

231.04

Pa

Protactinium

Identification

CAS Number: 7440-13-3

Discovery Year: 1917

Discoverer: Fredrich Soddy, John Cranston, Otto Hahn, Lise Meitner

Discovery Location: England/France

Properties

Atomic Mass: 231.03588 →Density: 15.4 g/cm³ →

Crust Abundance: 0.0000014 mg/kg

Crystal Structure: TET

Atomic Dimensions

Atomic Radius: 180 pm →

Atomic Radius (Rahm): 285 pm

Covalent Radius: 200 pm →

Van der Waals Radius: 243.00000000000003 pm

Atomic Volume: 15 cm³/mol

Lattice Constant: 3.92 Å

Thermodynamics

Melting Point: 2113 K →Boiling Point: 4300 K →Specific Heat: 0.121 J/(g·K) →Heat of Fusion: 16.7 kJ/mol →Heat of Vaporization: 481.2 kJ/mol →

Heat of Formation: 563 kJ/mol

Electronic Structure

Electron Config: [Rn] 5f2 6d 7s2

Block: f

Period: 7 →Electronegativity: 1.5 →

Oxidation States: +4, +5

Abundance & Geochemistry

Crust Abundance: 0.0000014 mg/kg

Sea Abundance: 5e-11 mg/L

Geochemical Class: U/Th decay series

Goldschmidt Class: litophile

About

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.