periotable.com is a free periodic table for students, teachers and anyone who needs a chemical fact they can trust. It covers all 118 elements in six languages — English, French, Spanish, Portuguese, Indonesian and Arabic — and every value on the site is traced back to the source it was taken from.
What you will find here
- The table itself, in four views: electron structure, physical properties, isotopes and compounds.
- A page for every element, with its key facts, measured properties, electron configuration and, for the most searched elements, a written article with cited sources.
- Pages for more than 600 isotopes in each language, covering every nuclide that is stable, occurs in nature, or lives at least a day.
- Fourteen calculators: molar mass, molarity, dilution, stoichiometry, pH, ideal gas, half-life, Lewis structures and more.
- Quizzes and reference tables — solubility, reactivity series, flame tests, polyatomic ions — and printable tables in colour, black-and-white and blank form.
Where the data comes from
We do not invent numbers. Atomic weights follow the IUPAC Commission on Isotopic Abundances and Atomic Weights, including the interval notation for elements such as carbon and hydrogen whose weight genuinely varies. Physical properties come from NIST reference data and the CRC Handbook. Isotope masses and half-lives come from the Atomic Mass Data Center evaluations. Element names in each language come from Wikidata, with corrections made by hand where the imported name was wrong.
Each value carries a link to its source and, where sources disagree, the site shows the disagreement rather than silently picking one. A value we could not verify is shown as unmeasured, not filled in with a guess.
Honesty about what has been reviewed
Translations of the interface and many articles have not yet been checked by a native-speaking chemist. Where that is the case, the site says so rather than hiding it. If a translation reads wrong to you, tell us — corrections from readers are how the site improves.
Who runs the site and how it is funded
periotable.com is an independent project, not affiliated with IUPAC, NIST or any university. It is built and maintained by a small independent team.
The site is free to use and is funded by advertising, served through Google AdSense. Advertising never influences the data or the content: no value on this site has ever been changed for a sponsor, and there are no sponsored articles. Read our privacy policy for how advertising cookies work and how to control them.
Contact
Write to us at contact@periotable.com or use the contact form. We reply to questions, corrections, and requests from teachers who want to use the material in class.