Chemistry & Biochemistry: Reference & Chemical Properties

ChemSpider is a free chemical structure database providing fast text and structure search access to over 67 million structures from hundreds of data sources.

Periodic table of the isotopes, atomic weights, isotopic abundances and other reference material from the International Union of Pure and Applied Chemistry (IUPAC).

The Substance Registry Services (SRS) is EPA's authoritative resource for information about chemicals, biological organisms, and others substance tracked or regulated by EPA.

Tables of constants typically found in textbook appendices or reference books are found here.

For over 120 years The Merck Index has been regarded as the most authoritative and reliable source of information on chemicals, drugs and biologicals. Now this trusted resource is available online from the Royal Society of Chemistry.

Easy access to chemical and physical property data for chemical species through the internet. The data provided in the site are from collections maintained by the NIST Standard Reference Data Program and outside contributors. Data in the WebBook system are organized by chemical species. The WebBook system allows users to search for chemical species by various means. Once the desired species has been identified, the system will display data for the species.

The Pillbox website was developed to aid in the identification of unknown pills. It combines images of pills with appearance and other information to enable users to visually search for and identify oral solid dosage for medications.

The Pistoia Alliance Chemical Safety Library (CSL) provides unique crowd sourced data content containing hazardous reactions that can be used to alert scientists to potential dangerous experiments. CAS, a division of the American Chemical Society, is committed to increasing safety in the lab and has provided this open access platform to serve scientists worldwide.

Mostly contains small molecules, but also larger molecules such as nucleotides, carbohydrates, lipids, peptides, and chemically-modified macromolecules. Information on chemical structures, identifiers, chemical and physical properties, biological activities, patents, health, safety, toxicity data, and many others.

Integrated spectral database system for organic compounds,which includes 6 different types of spectra under a directory of the compounds. The six spectra are as follows, an electron impact Mass spectrum (EI-MS), a Fourier transform infrared spectrum (FT-IR), a 1H nuclear magnetic resonance (NMR) spectrum, a 13C NMR spectrum, a laser Raman spectrum, and an electron spin resonance (ESR) spectrum.