THE ELEMENTS IN ACTION

There’s antimony, arsenic, aluminum, selenium….

This app is as light as helium. A precursor—please forgive the chemical pun—to TouchPress’ highly popular app The Elements (2010), it almost seems like a sales pitch for the much heftier parent publication. As it is, this app runs from 1 to 92, which is to say it runs from hydrogen to uranium but fails to go on to more recently discovered elements such as californium and nobelium. Whether this oversight is by design or whether the missing 10 (or, adding the three elements discovered this year, 13) will be added later is unknown; the same holds for the numerous elements between 1 and 92 that have no copy. Perhaps there’s nothing much exciting to say about technetium or scandium, but the lacunae are curious. What material there is, however, is unobjectionable but rarely engaging: Each element has a brief explanatory text (e.g., “Osmium is the densest element in the periodic table”) accompanied by a brief video—in the case of osmium, of a balance showing just how dense the stuff is. Occasionally the text takes odd turns (“The artist Salvador Dali would have liked the element gallium, although there is no record of him ever having played with it”), but it’s mostly straightforward stuff. Some of the videos are more commanding than others: That for rhenium shows a noisy arc furnace to demonstrate its high melting point, while that for copper, poor thing, shows a copper spoon being quickly eaten away by a dose of sulfuric acid. A 3-D sidebar shows the atomic structure of the element in question.

Absent the now-missing material, useful enough, though the interested reader might just as well go ahead and pay the extra $10 for the larger Elements app. (Requires iOS 7 and above.)