ChemPort
This site connects to full-text documents on the Web. - Chemweb.com
This Web resource is regarded as the worldwide club for the chemical community. Partial access is through free membership; other materials are provided through paid subscription. Its features include free structure searching, live 3-D molecules, and full-text searching. - ChemFinder
Search for chemical components by name, partial name or properties. Links are provided for more information on certain chemical compounds. - Chemical Scorecard
The Environmental Defense Fund provides free access to the type of value-added service that libraries usually pay for: collating, organizing, and interpreting data collected by the federal government. The Chemical Scorecard, created for the purpose of making pollution statistics more accessible, uses data from the EPA's Toxic Release Inventory plus other governmental and scientific agencies. The site's impressive documentation of data and sources is better than many reference books. - Eric Weisstein's World of Chemistry
- GrayLit Network: A Science Portal of Technical Reports
This is the world's most comprehensive portal to federal gray literature. - Links for Chemists
Indexes more than 7,500 chemistry Web resources in more than 60 categories. - NIST Webook
A gateway to the data collection of the National Institute of Standards and Technology (NIST). Provides access to the data compiled and distributed by NIST under the Standard Reference Data program. It contains thermochemical data for more than 5,000 organic and small inorganic compounds, reaction thermochemistry data for more than 8,000 reactions, Infra Red spectra for more than 7,500 compounds, Mass spectra for more than 10,000 compounds, UV/Vis spectra for more than 400 compounds, electronic and vibrational spectra to more than 3,000 compounds, constants of diatomic molecules for more than 600 compounds, and ion energetic data for more than 14,000 compounds - Science.gov
Directory of web sites dealing with science and math and a search engine. - Scirus
At this stage Scirus covers more than 60 million science related pages from the Web as well as membership sources such as ScienceDirect, MEDLINE on BioMedNet, Beilstein on ChemWeb and Neuroscion. Scirus delivers relevant search results because it focuses on scientific information only, indexes complete documents, searches the whole Web including access-controlled sites, and reads non-text files like PDF. - Web Elements
This is one of the most up-to-date and complete periodic tables on the Web.
Professional Organizations