Britannica Nobel Prize: Radium
Detailed overview and data.
ChemicalElements.com: Radium
Basic information, atomic structure, and isotopes.
EnvironmentalChemistry.com: Radium
Atomic structure, chemical and physical properties, and table of nuclides.
It's Elemental: Radium
Basic physical and historical information.
Lenntech: Radium
Physical data, chemical properties, health and environmental effects.
Radiochemistry of Radium
Full text of the monograph by Murrell L. Salutsky (W.R. Grace & Co., Research Division, Washington Research Center, Clarksville, Maryland) and H. W. Kirby (Mound Laboratory, Miamisburg, Ohio). [PDF]
Visual Elements: Radium
Image, general and physical information, source, uses, key isotopes, and ionisation energies.
WebElements: Radium
Extensive information on history, uses, occurrence, compounds, and properties.
Wikipedia: Radium
Properties of the element, including its history, applications, and charateristics.