Why are some triatomic molecules linear (carbon dioxide, hydrogen cyanide) and others are bent (water, sulfur dioxide)? And why is the bond angle in water (~105°) smaller than that in sulfur dioxide (~119°)? Valence Shell Electron Pair Repulsion (VSEPR) theory provides surprisingly simple explanations in terms of the electron pairs that surround the central atom of a given molecule. VSEPR theory is described in detail in every introductory chemistry book.

The ODYSSEY VSEPR Theory app provides three-dimensional models of 50 small molecules and ions as well as a set of generic models that illustrate the conceivable geometries of the theory. Each model can be moved and manipulated with simple touch gestures. Bond lengths and bond angles can be queried.

Users can pick from multiple model styles (such as Ball and Spoke or Space Filling), request a schematic display of lone pair positions, and show the molecular dipole arrow. A glossary, comments section, and a set of multiple-choice questions (with randomized options) are also available.

Most learners of chemistry are visually oriented. Complementing the presentation found in any introductory textbook, ODYSSEY VSEPR Theory enables exploration of one of the most fundamental concepts in general chemistry—molecular shape.

“3D Molecules Edit & Test” allows one to build and manipulate 3D molecular models of organic and inorganic compounds. The key features of “3D Molecules Edit & Test” are 3D printing support and the "Test yourself" mode that allows learners to check their knowledge of the 3D structure of molecules. This is a valuable tool for chemistry students when learning about molecular bonding and orbitals with the aid of 3D visualisation. The app is great for any high school or college student in chemistry courses.

The Medicinal Chemistry Toolkit app is a suite of resources to support the day to day work of a medicinal chemist. Based on the experiences of medicinal chemistry experts, we developed otherwise difficult-to-access tools in a portable format for use in meetings, on the move and in the lab. The app is optimised for iPad and contains calculator functions designed to ease the process of calculating values of: Cheng-Prusoff; Dose to man; Gibbs free energy to binding constant; Maximum absorbable dose calculator; Potency shift due to plasma protein binding; Log D vs pH curves; Attrition Modeller, Drug-drug interactions; GClogP, Ligand Lipophilic Efficiency and compound quality calculations.


Chemical Valence is an app designed to help you learn the basics about chemical bonding. This app provides a fun game-like, intuitive interface in which you push valence electrons around to make molecules. If you form the correct 2D Lewis dot structure, you are rewarded with a rotatable 3D structure that helps you visualize the real geometry of the molecule. As your understanding grows, each level gives you more complicated structures to solve. Use the narrative, definitions and open-ended reflection questions (with hints!) to guide your understanding. This app is suitable for individual study or for use in a classroom.