Fans of The Solar System, The Elements, and other apps from Touch Press, should have an inkling about what to expect from Theodore Gray and Molecules. In the review below you'll find out about a new technology that allows scientists—and you—to view simulated models of molecules—views seen before only in a "very few laboratories." A new app from Touch Press—home of the exquisitely lit razor-sharp 360-degree image floating on a velvet-black background—is like getting a VIP tour of a fabulous new exhibit at a richly funded museum. It will be dark. Things will gleam. The wall labels will be fascinating. And, because you are very very lucky, the curator providing the tour will be witty, vastly well-informed, and possessed of a boundless well of anecdote. Here's Theodore Gray in Molecules (iOS $13.99; Gr 9 Up) making a point about the relative safety of synthetic compounds versus natural ones: "Molecules don't know where they came from. They just are. They don't know if they are natural or artificial, good or evil, wholesome or poisonous. Whether they were created in a lab, in the venom gland of a sea snail, in a factory, or in the leaf of an herb simply has no bearing on the question." (Gray consumes neither aspartame nor "random mushrooms that I find in the forest," preferring to give synthetic compounds "a few decades to shake out," and noting that there many toxic substances to be found in the natural world.) And like a really good museum exhibit, there are rewards here for both casual visitors and the serious seekers of knowledge. Chapters on color, scent, sugars, and pain versus pleasure start with our own perceptions and show how molecular compounds can manipulate them. Why does ibuprofen dull our headache? What colors do bees see? Further exploration leads users to cogent explanations of chemical bonds, molecular building blocks and families of molecules, and what makes a molecule relatively stable or relatively volatile. We see an ant's vocabulary spelled out in straight-chain hydrocarbon pheromone molecules (it's somewhat monotonous). And the serious student of chemistry will benefit from the first public utilization of a technology that "accurately model[s] the physical behavior of individual molecules." Called NAMD, it allows users to bend and flex the 3-D models of molecules in the app, demonstrating the molecule's structural characteristics and even the relative flexibility of different types of molecular bonds. Powerful and pretty.—Paula Willey, Unadulterated.Us For additional app reviews, visit our dedicated Touch and Go webpage.