Ra

Radium

Identification

CAS Number: 7440-14-4

Discovery Year: 1898

Discoverer: Pierre and Marie Curie

Discovery Location: France

Properties

Atomic Mass: 226 →Density: 5 g/cm³ →

Crust Abundance: 9e-7 mg/kg

Atomic Dimensions

Atomic Radius: 215 pm →

Atomic Radius (Rahm): 292 pm

Covalent Radius: 221 pm →

Van der Waals Radius: 283 pm

Atomic Volume: 45 cm³/mol

Thermodynamics

Melting Point: 973 K →Boiling Point: 1413 K →Specific Heat: 0.12 J/(g·K) →Heat of Fusion: 9.6 kJ/mol →Heat of Vaporization: 113 kJ/mol →

Heat of Formation: 159 kJ/mol

Electronic Structure

Electron Config: [Rn] 7s2

Block: s

Period: 7 →Group: 2 →Electronegativity: 0.9 →Electron Affinity: 0.1 eV →

Oxidation States: +2

Abundance & Geochemistry

Crust Abundance: 9e-7 mg/kg

Sea Abundance: 8.9e-11 mg/L

Geochemical Class: U/Th decay series

Goldschmidt Class: litophile

About

Radioactive metallic transuranic element, belongs to group 2 of the periodic table. Most stable isotope, Ra-226 has a half-life of 1602 years, which decays into radon. Isolated from pitchblende in 1898 Marie and Pierre Curie.

Isotopes

Ra-226 226 ☢ 1.60e+3 a

Ra-228 228 ☢ 5.75 a