Miscellaneous`ChemicalElements`
New function ElementData has been added to the built-in Mathematica kernel.
Many functions from Miscellaneous`ChemicalElements` are now available as properties of ElementData:
Version 5.2
ElementData["Properties"] gives a list of all properties available for chemical elements:
Miscellaneous`ChemicalElements` was available as an add-on package in previous versions of Mathematica and is now available on the web at library.wolfram.com/infocenter/MathSource/6794.