Two different Periodic Table clocks displays: 

The simple clock display shows the Atomic Number and either Atomic Weight or Name. Colors indicate Phase: Solid, Liquid, or Gas. Tap to toggle seconds on or off; long-press to switch between Atomic Weight and Element Name.

The Complete clock display shows all available information about each element.

There's also a scrollable reference view that shows all of the elements, which can be set up as flashcards to test your knowledge.