Chemistry is typically defined as the science that studies the composition, structure, and transformation of matter.
It has been called "the central science" because of the way it is related with all the other sciences. Chemistry bridges the gap between physics and biology; it is a "helper science" in almost many technical disciplines; and it occupies a prominent position in industry between the extraction of raw materials and the manufacture of finished products. Of course, it is chemists who call it this way; other scientists may have different perspectives.
Chemistry is also distinguished from some other sciences because it creates its own object of study: chemists can imagine and create new compounds that have never existed in nature, so they are not constrained to what already exists, but only to what can be done.
Online textbook, lab activities, detailed information on selected topics, history sections including timelines and brief biographies. http://www.3rd1000.com/3rd1000.htm
Providing information on all facets of the world-wide chemical industry. Many links to web resources of interest to chemists and the chemical industry. http://www.neis.com/
Maintained by the University of Liverpool, this free, searchable chemistry index carries in excess of 8,250 chemistry resources in over 75 chemical categories. http://www.liv.ac.uk/Chemistry/Links/links.html
Chemsoc, the chemistry societies' network, provides a gateway to the best chemistry information and resources on the web. http://www.chemsoc.org/chembytes/
Site designed to help people find and learn how to use chemical information resources on the Internet and elsewhere. Email discussion list available. http://www.indiana.edu/~cheminfo/