The Chemical Touch App for iOS
'Explore the properties of the elements, the standard amino acids, and the nucleobases with The Chemical Touch. A touch sensitive periodic table and chemical information companion, it provides a wealth of information right at your fingertips. Recolor the periodic table by selecting properties other than Atomic Mass to visually investigate periodic trends. Having exhausted the built-in information, the internet button opens the Wikipedia page for the selected element, amino acid, or nucleobase.
A quick guide detailing all the features is available for download at the application website.'
This app costs $0.99