Sodium
Links
Visual Elements: Sodium
http://www.chemsoc.org/viselements/pages/sodium.html
Image, animation, source, uses, key isotopes, and ionisation energies.
Radiochemistry of Sodium
http://lib-www.lanl.gov/cgi-bin/getfile?rc000010.pdf
Full text of the monograph by W. T. Mullins and G. W. Leddicotte (Oak Ridge National Laboratory, Oak Ridge, Tennessee). [PDF]
It's Elemental: Sodium
http://education.jlab.org/itselemental/ele011.html
Basic physical and historical information.
ChemicalElements.com: Sodium
http://www.chemicalelements.com/elements/na.html
Basic information, atomic structure, and table of isotopes.
EnvironmentalChemistry.com: Sodium
http://environmentalchemistry.com/yogi/periodic/Na.html
Atomic structure, chemical and physical properties, and table of nuclides.
WebElements: Sodium
http://www.webelements.com/webelements/elements/text/Na/key.html
Extensive information on history, uses, occurrence, compounds, and properties of the element.
Wikipedia: Sodium
http://www.wikipedia.org/wiki/Sodium
Properties of the element, including its history, applications, and charateristics.
Lenntech: Sodium
http://www.lenntech.com/Periodic-chart-elements/Na-en.htm
Physical data, chemical properties, health and environmental effects.