So far I have found two pretty good Periodic Table of Elements (PTE) apps available for free for iPads,  One is called 'Periodic Table of Elements' and is made by Kevin Neelands.  It has your basic information including the oribitals, states, and a diagram of the electrons and protons.  It also has a simple way of grouping the elements visually by metal, melting point, boiling point, and native state.

Another, more elegantly designed PTE is EMD Chemicals 'EMD PTE.'  It has a more refined color palette and navigation system.  It also contains more detailed information per element.  EMD PTE has a really nice classification system where you can choose different filters to apply to the table to see which elements fall under certain categories.

Both tables would be great for any middle school science class or high school chemistry class.