Barium
Links
Visual Elements: Barium
http://www.chemsoc.org/viselements/pages/barium.html
Image, appearance, source, uses, key isotopes, and ionisation energies.
It's Elemental: Barium
http://education.jlab.org/itselemental/ele056.html
Basic physical and historical information.
ChemicalElements.com: Barium
http://www.chemicalelements.com/elements/ba.html
Basic information, atomic structure, and isotopes.
Wikipedia: Barium
http://www.wikipedia.org/wiki/Barium
Properties of the element, including its history, applications, and charateristics.
EnvironmentalChemistry.com: Barium
http://environmentalchemistry.com/yogi/periodic/Ba.html
Atomic structure, chemical and physical properties, and table of nuclides.
WebElements: Barium
http://www.webelements.com/webelements/elements/text/Ba/key.html
Extensive information on history, uses, occurrence, compounds, and properties.
Lenntech: Barium
http://www.lenntech.com/Periodic-chart-elements/Ba-en.htm
Physical data, chemical properties, health and environmental effects.