UniServe*Science News: Newsletter of the Science Software Clearinghouse Vol 1, July 1995

WebElements: A Chemistry tool on the Web

Greg Warr is a Senior Lecturer in Physical Chemistry in the School of Chemistry at the University of Sydney

WebElements is a periodic table database available on the World Wide Web through several sites, including one at the Australian Defence Force Academy. The home page displays a periodic table in standard format forming a hypertext link to a separate data page. There are also references and links to other periodic table databases, which may differ somewhat from WebElements in presentation.

The home page also contains links to two utilities: an isotope pattern calculator and a mass composition calculator. Both are located at the University of Sheffield, and operate by the user typing a formula, e.g. C6H40, and pressing Enter. The isotope patterns or elemental abundances are returned on a new page.

The main game is however the elemental data, which is presented as a single scrollable page for each element. This is fairly comprehensive and correct as far as I could see, but the data sources were not cited. Listed first are atomic number, weight, symbol, and some general information in such as standard state, colour, and details of the element's discovery. Scrolling down the page reveals atomics and ionic radii for various states, electronegativity, and effective nuclear charge, bond enthalpies, melting, boiling and critical temperatures, enthalpies of phase transitions and of ionisation, finally showing isotopic abundances.

While the data for each element is presented clearly, the organisation is inconvenient. As was suggested to me, a set of sub-headings which could be expanded via a hypertext link might make it easier to navigate to the data you might what than the single page per element.

This makes WebElements a useful database, but with limited application in science education. If you want data on an element you should be able to find it. However more often one would like to be able to compare properties across a row or down a group of the periodic table, so a database permitting more sophisticated searching and comparison would be better in this context. This is in some ways a limitation of the web rather than WebElements: A more complex database would mean more memory and slower access. I am not even certain how far one can take html in this direction.

However, if you want elemental data, it is available on WebElements. Moreover, it's free, so you can look for yourself and determine how you might use it. I'm not sure that I'll use it very much, but it's nice to know it's out there.

Greg Warr

WebElements can be found at the URL http://apamac.ch.adfa.oz.au/ozchemnet/web-elements/

For further information on the World Wide Web see the article on the Web earlier in this newsletter.

Sites of Interest

The NIH Molecular Modeling Home Page

MacroModel Home Page

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