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Privacy Policy

Last reviewed 9 October 2026.

This is a static reference site. Pages are pre-built and served as files, there is nothing to log into, and this site itself keeps no record attached to anyone who simply reads it. What follows is the complete list of places where data is involved at all, the advertising among them, which is run by Google rather than by this site.

The five places data is involved at all

Aggregate page counts. The site records how many times each page is viewed, through Vercel Web Analytics and Google Analytics 4 with its cookie storage switched off, so neither sets a cookie, builds a cross-site profile or stores an identifier that could single you out on a later visit. What comes back is a count per page, per day. It is used to decide which element pages deserve more work.

Hosting logs. The host, Vercel, keeps short-lived request logs containing IP addresses and browser user-agent strings, in the ordinary way that any web server does, for delivery and abuse-prevention purposes. Those logs are not read for analytics and are not combined with anything else here.

Advertising, through Google. Display ads are served by Google AdSense, which sets cookies of its own. The Advertising section below explains what that involves and how to switch personalisation off.

The newsletter, if you subscribe. Subscribing stores the email address you type and the date you gave it, through Brevo, which handles the sending. A welcome message goes out immediately; after that it is the occasional note and nothing else. Nothing further is asked for and nothing else is inferred. Every message carries an unsubscribe link that removes the address rather than flagging it, and an address is never sold, rented, shared or used to reach you about anything other than this site.

A purchase, if you make one. Payment for the printable pack is handled entirely by Stripe. Card details are entered on Stripe's own infrastructure and never reach this site or its host, and no record of the payment is sent back to this site either. The order is read from Stripe's own dashboard, and the file is sent by hand to the address given there. Stripe collects the name, billing details and payment information required to process a card transaction, and Stripe's own privacy terms govern that. There is no account to create and no stored payment method.

What the calculators do with what you type

Nothing leaves your device. The molar mass, percent composition, equation balancing and configuration tools all run as JavaScript in your browser, computing from data that was shipped with the page. Formulas and equations you enter are not transmitted anywhere, not logged and not retained after you close the tab.

Advertising

This site carries display advertising served by Google AdSense to cover hosting. Google and its partners set cookies to deliver and count those ads; with personalisation allowed, the ads can also be tailored to your visits to this site and to others. Readers in the EEA or the UK are asked by Google for their consent before any personalised-advertising cookie is set, and the choice can be changed at any time.

Advertising never influences what an element page says. No property value, discovery story or safety note is chosen with a sponsor in mind, and pages go up without any advertiser having seen them first. Some element pages also link to safe samples, such as metal cubes or a bismuth crystal, and to a book about the elements on Amazon as an affiliate; the affiliate disclosure sets out the rules.

To see why an ad appeared, or to switch off personalised ads, use Google My Ad Center, or opt out of interest-based advertising from many companies at once at aboutads.info. Google explains its advertising cookies at policies.google.com/technologies/ads.

What is deliberately absent

  • No sponsored content and no paid placement in the reference itself. The display advertising described above is clearly an ad, and it never influences what an element page says.
  • No user accounts, no comments and no user-submitted content. There is no profile to build because there is no profile.
  • No social media embeds or third-party widgets beyond the Google analytics and advertising scripts described above.
  • No sale of personal information. Nothing collected here is sold to anyone, and Google's advertising cookies can be switched off with the opt-outs in the Advertising section.

Mail you send

An email sent to the address on the contact page arrives in an ordinary mailbox and is kept for as long as it is useful — typically until whatever it raised is resolved, and longer where it produced a correction that someone might later query. The form on that page is delivered by Brevo, the newsletter's email provider, which sends what you write to that same mailbox and keeps a delivery record of it in doing so. Either way, messages are not added to the newsletter list.

Children

Nothing here is directed at children under 13, and no information is knowingly collected from them. The site is used by school-age students constantly, which is precisely why it asks for nothing in order to work.

Your rights, and how to use them

If you are in the UK, the EU, California or anywhere with comparable law, you can ask what is held about you, ask for a copy, ask for it to be deleted, and withdraw consent for the newsletter at any time. In practice the answer for most readers is that nothing is held.

Requests go to the contact address. There is no identity-verification process beyond replying from the address in question, because an email address is the only identifier there is.

If this policy changes materially, the date at the top changes with it.