What does the unit cell of sodium chloride look like? How is its structure different from other salts? What relationship, if any, exists between the structures of ionic and metallic solids?

ODYSSEY Ionic Solids is a three-dimensional visualization aid that expands on standard textbook concepts of the structure of ionic crystals. Generic models and concrete examples are provided for twelve structure types: sodium chloride, cesium chloride, zinc blende, wurtzite, fluorite, rutile, nickel arsenide, cadmium chloride, cadmium iodide, calcium chloride, perovskite, and spinel. Unit cells are presented, coordination numbers are highlighted, and the occupancy of cations in the sublattice of anions is illustrated. Models of the cubic structure types for metals (simple cubic, body-centered cubic, and face-centered cubic) are available for comparison. In total, more than a hundred models are available.

All models can be inspected at any orientation and zoom level and with a choice of the drawing radius for the ionic spheres. For any given ion, a “clipping sphere” can be defined that highlights the local surroundings of that ion and hides the remaining structure. Distances between ions can be measured, and a display of ionic charge labels is available. A glossary, comments section, and set of multiple choice questions (with randomized options) are also included.

The structural patterns presented in ionic compounds are not easily appreciated without looking at concrete models. ODYSSEY Ionic Solids helps familiarize learners with the subject and gain the experience needed to explore new structures.

How different are double and triple bonds from single bonds? And what do double-bonded molecules with multiple Lewis structures―such as ozone, nitric acid, and benzene―look like?

ODYSSEY Multiple Bonds and Resonance is a visualization app that uses the results of rigorous quantum chemical calculations in order to fight pervasive misconceptions about molecular structure. Models of 51 simple molecules and ions are provided, both inorganic and organic. Each model can be manipulated in 3D with simple gestures. Bond lengths and bond angles can be queried.

The user can pick from conventional model styles such as Ball&Spoke and Space Filling. Surpassing schematic representations, the electron clouds can also be displayed as isosurfaces of the electron density. A table of standard bond lengths, glossary, comments section, and a set of multiple-choice questions (with randomized options) complete the app.

Resonance is a core concept of chemistry that is surrounded by mystery. Working with ODYSSEY Multiple Bonds and Resonance and taking an inquiry-based approach can help provide a clearer understanding of the subject.

What would molecules look like if we could dive in and inspect them on the atomic scale? Would they look anything like the structural drawings in textbooks? Would they resemble the three-dimensional Ball&Stick models from plastic model kits and computer-based visualizers?

ODYSSEY Electron Sharing presents molecular models where ad hoc “bonds” are deliberately not shown. In fact, the visualization includes nothing but the nuclei and the electron cloud, with the latter represented as a series of isosurfaces of the electron density. As the underlying data have been obtained from rigorous first principles calculations, the models provide an unbiased, “raw” view of a number of common substances.

Models are included for a single water molecule, an interacting pair of water molecules, and a corresponding droplet-like cluster. Multiple electron density surfaces are also provided for an assortment of 30 molecules, ions, and bulk samples. Intuitive gestures allow for inspection of all models at any orientation and zoom level. Statements regarding the presence or absence of bonds can be made quantitative by measuring distances and angles. A glossary, comments section, and a set of multiple-choice questions (with randomized options) are also available.

Complementing the presentation of covalent bonding in any chemistry textbook, ODYSSEY Electron Sharing adds a perspective of molecular chemistry that is rarely, if ever seen.

How do electronegativity differences affect the type of bonding in chemical compounds? Why do some (but not all) molecules have dipole moments? If a molecule has polar bonds, does that mean it is a polar molecule?

ODYSSEY Polar Bonds and Molecules takes an entirely visual approach to distinguishing between nonpolar, polar covalent, and ionic compounds. Quantum chemical calculations are employed to present electron density distributions for more than thirty systems. The distributions are also available as color-coded polarity maps (electrostatic potential maps). Pioneered by Wavefunction’s Spartan software and utilized in countless textbook illustrations, such maps provide an immediate and intuitive feel for the polarity and reactivity of compounds.

Using simple gestures, all models can be inspected at any orientation and zoom level. Different styles are available for the display of both molecules and electronic distributions. Bond distances and bond angles can be measured, the molecular dipole arrow can be shown, and a display of atomic charge labels can be requested. A glossary, comments section, and set of multiple-choice questions (with randomized options) are also available.

ODYSSEY Polar Bonds and Molecules helps in becoming familiar with the dichotomy of covalent and ionic bonding that is central to chemistry. The app also offers concrete examples to show how polar bonds in a molecule may (or may not) give rise to a compound that is polar.