I regularly get questions from people wondering if The Elements or Molecules is, or will be, available as an app for Android devices, as it is for iPads. The answer so far is always no, sorry, there are no plans for an Android version. (The basic problem is that Android devices and stores are very fragmented, with hundreds of different versions to support. We just don't think we could recover the cost of making an Android version.)
But despite that, there is now a version of The Elements available for basically ALL tablet/ebook reader devices, including all Android devices. The catch is that it's a static, traditional ebook, not the fully interactive app version available for iPads. The main difference is that in the app version you can spin all the objects with your finger, while in the static ebook version each object gets just a single photo, like in the print book.
But other than that, it's the same book: Same text, same objects, same everything. Many people might actually prefer the static ebook to the app, because it is completely flexible with regards to font, font size, background color, etc. (It looks best on a black background, but if you find that hard on your eyes, most ebook readers let you adjust all kinds of things about how the text is displayed.)
Here are links to the English-language static ebook version in as many stores as I could find it in. If you have a different kind of device, or want it in a different language, you can probably find it by searching for "Elements Theodore" (or "Atomes Theodore" in French) in your store/torrent site. (If you intend to pirate it, OK, but I hope you're doing that because you hate me and don't want me to get any of your money, not just because you're cheap.)
For iPad/iPhone users, note that there are now two different versions you can get: The interactive app, and the static ebook. Which should you get? Well, the app takes up about 1.7GB of space, lets you rotate all the samples and see them in stereo 3D, and includes The Elements song by Tom Lehrer in both English and Japanese. The static ebook is about 82MB (i.e. Way WAY smaller), includes all the same text, but just one image per object and no song. You buy the app in the App Store and the static ebook version in the iBookstore. (Sorry, there is no practical way we can offer you both for one price: Those are completely different stores, and completely different products.)
If you're wondering about my new book, Molecules, that is currently available only as a print book and as an iPad app, but some time in the future, can't promise when, it will also come out as a static ebook.