ODYSSEY VSEPR Theory vs WebMO Premium

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.

WebMO Premium is equivalent in functionality to the free 'WebMO' app in conjunction with the 'WebMO Premium' in-app purchase. This paid version is provided for convienence for volume purchases. WebMO allows users to build and view molecules in 3-D, visualize orbitals and symmetry elements, lookup chemical information and properties from external databases, and access state-of-the-art computational chemistry programs. WebMO is recommended for students and faculty in high school, college, and graduate school who desire mobile access to molecular structures, information, and calculations. WebMO capabilities include: - Build molecules by drawing atoms and bonds in a 3-D molecular editor, or by speaking the name (e.g., “aspirin”) - Optimize structures using VSEPR theory or molecular mechanics - View Huckel molecular orbitals, electron density, and electrostatic potential - View molecular vibrations - View point group and symmetry elements of molecules - Lookup basic molecular information, including IUPAC and common names, stoichiometry, molar mass - Lookup chemical data from PubChem and ChemSpider - Lookup experimental and predicted molecular properties from external databases (NIST, Sigma-Aldrich) - Lookup IR, UV-VIS, NMR, and mass spectra from external databases (NIST, SDBS) - Capture high-resolution molecular images - Save and recall molecular structures locally - Export and import structures via email WebMO is also a front-end to WebMO servers (version 14 and higher): - Supports Gaussian, GAMESS, Molpro, MOPAC, NWChem, ORCA, PQS, PSI, Quantum Espresso, VASP, Q-Chem, and Tinker computational chemistry programs - Submit, monitor, and view calculations - View formatted tabular data extracted from output files, as well as raw output - Visualize geometry, partial charges, dipole moment, normal vibrational modes, molecular orbitals, and NMR/IR/UV-VIS spectra