The ChemBasics app provides hundreds of opportunities to write inorganic formulas, write and balance chemical equations, and perform mass-mass calculations. Immediate feedback is provided with every item. Access to the correct result is a finger touch away. The simplicity of the interface allows the user to focus on chemistry. View animations of app operation and access additional resources at chemistryapp.org. This app runs on IOS 8.4 for iPhone, iPod and iPad. This method of learning or teaching chemistry has been successfully demonstrated on classroom computers over a ten-year period all over the US. This is our fourth app to go mobile.