Actinium
Links
Visual Elements: Actinium
http://www.chemsoc.org/viselements/pages/actinium.html
Image, sources, biological role, key isotopes, and oxidation states.
It's Elemental: Actinium
http://education.jlab.org/itselemental/ele089.html
Basic physical and historical information.
EnvironmentalChemistry.com: Actinium
http://environmentalchemistry.com/yogi/periodic/Ac.html
Atomic structure, properties, and table of nuclides.
ChemicalElements.com: Actinium
http://www.chemicalelements.com/elements/ac.html
Basic information, atomic structure, and isotopes.
Actinium
http://www.scescape.net/~woods/elements/actinium.html
Data tables and historic information.
Wikipedia: Actinium
http://www.wikipedia.org/wiki/Actinium
Details the properties of the element, including its history, applications, and charateristics.
WebElements: Actinium
http://www.webelements.com/webelements/elements/text/Ac/key.html
Extensive information on history, uses, occurrence, compounds, and properties.
Lenntech: Actinium
http://www.lenntech.com/Periodic-chart-elements/Ac-en.htm
Physical data, chemical properties, health and environmental effects.