Privacy Policy
How this site handles data, cookies and advertising — including Google AdSense, the DART cookie and how to opt out of personalized ads.
Last updated: November 1, 2026
Scope of this policy
This policy explains what data chem.5l5l.net and its third-party partners collect when you visit the site, and what you can do about it. By using the site you agree to the practices described here.
Information we collect directly
We do not ask for, and do not require, any personal information to use this site. There is no registration, no newsletter and no account system.
Our web server records standard technical logs — IP address, timestamp, requested URL, user agent and referrer — for the sole purpose of keeping the service available and diagnosing faults. These logs are retained for a short period and are not combined with any other dataset or shared with advertisers.
Cookies and advertising
Third-party vendors, including Google, use cookies to serve ads based on your prior visits to this and other websites.
Google's use of advertising cookies enables it and its partners to serve ads to you based on your visit to this and/or other sites on the internet. You may opt out of personalized advertising by visiting Google Ads Settings.
You can opt out of a third-party vendor's use of cookies for personalized advertising at aboutads.info for participating vendors, or via your browser's cookie settings. You can also change your choices in the consent banner shown to visitors in the European Economic Area and the United Kingdom.
If you opt out, ads will still be served in some cases — they simply will not be personalized to you.
The DART cookie
Google may use the DoubleClick DART cookie to serve ads based on your previous visits to this or other websites. You may decline this cookie by visiting Google Ads Settings and choosing the appropriate opt-out, or by visiting aboutads.info. Doing so does not affect the content available on this site.
Analytics
We use Google Analytics to measure aggregate, anonymized traffic so that we know which pages are useful. We do not use it to build advertising profiles of individual visitors, we do not sell analytics data, and IP addresses are anonymized before storage.
European Economic Area and United Kingdom rights (GDPR)
Visitors in the EEA and the United Kingdom are shown a consent banner before any non-essential advertising cookie is set. Rejecting the banner leaves the site fully functional — the periodic table, every element page, search and all reference data remain available.
If you are in the EEA or the United Kingdom, you have the right to access, correct, delete or restrict processing of your personal data, to object to processing, to data portability, and to lodge a complaint with your local supervisory authority. Because we do not maintain accounts, we hold no personal data tied to your identity; requests relating to server logs are handled by the email address below and are answered within 30 days.
We do not sell personal information and we do not share it with third parties for their own independent purposes.
Children's privacy
This site is a general-audience chemistry reference and is not directed at children under 13. We do not knowingly collect personal information from children. If you believe a child has provided us with personal information, contact us and we will delete it.
Third-party links and embedded content
Some pages link to external resources, including PubChem and Wikidata. We are not responsible for the privacy practices of sites we do not control; please review their own policies.
Changes to this policy
We update this policy when our data practices change or when the law requires it. The revision date is shown at the top of this page, and material changes are announced on the site.
Contact us
Questions about this policy, or a privacy request, can be sent to the address below.