In this animated and interactive object, learners observe how two, three, or four groups of electrons around the central atom cause the shape of the molecule to be linear, trigonal planar, bent, tetrahedral, or pyramidal. Seven examples and eight interactive questions are provided.

Learners examine the method used to calculate the mass percent of an element in a compound. Three examples and one problem illustrate the method.

In this interactive and animated object, learners use solubility rules to predict when an insoluble ionic compound will precipitate in a double replacement reaction. Step-by-step examples are given.

Learners examine how chemists use moles to "count" atoms by weight. Examples are given.