[Very basic data, requires Javascript] Interactive table with pictures of the elements.

[Very comprehensive, includes very detailed write ups, basic nuclide data, extensive graphics] Professional scientists and students at school will all find something useful. Includes thousands of images relating to periodicity and structure.

[Very basic data] Predicted periodic table for undiscovered elements with atomic number greater than 118. Theoretical discussion and Orbital freeware available.

[Basic data] Interactive periodic table. Including uses and discovery.

[Basic data] Quiz that involves remembering symbols. Includes copy of periodic table with data.

[Basic data, includes printable version] Information on each of the chemical elements and data on their properties. Some site information is only in Czech language.

[Very Comprehensive data] Interactive periodic table. Includes additional information on ionisation energies, abundance, isotopes and reduction potentials.

[Basic data] Simple click on periodic table. Includes electrical conductivity and ionization energies.

[Very comprehensive data, write-ups, extensive listing of nuclides] Data on elements includes scores of properties, element names in a dozen languages and almost all known nuclides. Environmental chemistry articles round out site.

[Nuclide data only, very extensive listing of nuclides] Map of all known nuclides, with their atomic mass, radioactive decay modes and half-lives, and related information. Brookhaven National Laboratory.