Chemistry Keyboard is a keyboard extension, usable within almost any app in iOS with keyboard entry that makes typing chemical formulae fast. I've been told that it's faster than typing on a desktop Mac.
Type out formulas like 2•CaCO₃+Mg²⁺↔︎CaMg(CO₃)₂+Ca²⁺ right into Messages, Pages, Safari or almost any app you choose.
