We run a trivia game called Pair5. It's available on iOS, Android and web, and you can compete against both friends and people you don't know, and also practice by yourself as much as you want. While Pair5 is a general knowledge game, some of the quiz categories are chemistry related.
Pair5 has a Try-it mode where you can play a selection of chapters without creating an account. The following are about chemical elements:
Click the links above to test your knowledge of chemical elements!