Chemistry

An online dictionary of chemical terms including interactive features.

Open community resource for accessing chemical information. From CAS REGISTRY® including common and frequently regulated chemicals.

Owned by the Royal Society of Chemistry., ChemSpider is a free chemical structure database providing fast access to over 100 million structures, properties, and associated information.

PubChem is an open chemistry database at the National Institutes of Health (NIH).
"PubChem mostly contains small molecules, but also larger molecules such as nucleotides, carbohydrates, lipids, peptides, and chemically-modified macromolecules. We collect information on chemical structures, identifiers, chemical and physical properties, biological activities, patents, health, safety, toxicity data, and many others."

Open-access collection of crystal structures of organic, inorganic, metal-organic compounds and minerals, excluding biopolymers.