Basic information, atomic structure, and isotopes.

Atomic structure, chemical and physical properties, and table of nuclides.

Basic physical and historical information.

Sources, properties, isotopes, and uses.

Physical data, chemical properties, and health effects.

Full text of the monograph by G. W. Leddicotte (Oak Ridge National Laboratory, Oak Ridge, Tennessee). [PDF]

Data tables and historic information.

Image, source, uses, physical information, and key isotopes.

Extensive information on history, uses, occurrence, compounds, and properties of the element.

Properties of the element, including its history, applications, and characteristics.