Overview and basic data.

Basic information, atomic structure, and table of isotopes.

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

Basic physical and historical information.

Sources, properties, uses, and isotopes.

Physical data, chemical properties, health and environmental effects.

Data tables and historic information.

Full text of the monograph by P. E. Figgins (Mound Laboratory, Miamisburg, Ohio). [PDF]

Image, general and physical information, source, uses, key isotopes, and ionisation energies.

Extensive information on history, occurrence, compounds, and properties.

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