This is an interactive periodic table (chemistry reference table).
At the time, I could not find a ready-to-use XML source for the elements and their various properties. I could not even find a traditional database source. So I spent a long time accumulating the data from various sources, including Wikipedia and many others. I am happy to provide these XML files to anyone interested:
Element List (Main Chart) XML
Element List (Sub Chart) XML
General Properties XML
Atomic Properties XML
Physical Properties XML
Misc. Properties XML
If you find an error or data item that needs to be updated, please let me know: firstname.lastname@example.org.
Here is another terrific interactive periodic table, by Michael Dayah.
Of course, you are invited to explore my blog, Excel Hero.