Properties of Substances

Spectral and Physical Properties (NIST)

This is a good source of thermodynamic data.

Organic Compound Spectra (SDBS)

This is a database of IR, NMR and Raman Spectra from the National Institute of Advanced Industrial Science and Technology of Japan. Includes some inorganic compounds as well.

NASA Raman Spectral Database

Atomic Weights and Isotopes (NIST)

High precision isotope masses.

Computational Chemistry Comparison and Bench Mark Databases (NIST)

NIST web site which has information useful for comparing computational methods. Includes geometries and some other molecular properties.

What is that Stuff?

A site maintained by the American Chemical Society that tells what is in many common consumer products.