NIST Chemistry WebBook (National Institute of Standards and Technology)
NIST site provides chemical and physical property data on over 40000 compounds.
Perform a Chemical Name Search - Chemical Formula Search - CAS registry number.
CAS - Chemical Abstracts Service A division of the American Chemical Society which provides chemical information and a registry containing information on more than 71 million organic and inorganic substances...
CRC Handbook The content of the 94thEdition of the CRC Handbook of Chemistry and Physics available online.
Wikipedia is a great tool for a summary of a topic. Wikipedia content is constantly revised, and entries vary in quality. Some of the content is excellent, some is questionable.
Many educators frown on the use of Wikipedia. Why?
How can you use Wikipedia in a way that benefits your research process?