VSEPR theory. VSEPR theory is usually compared with valence bond theory, which addresses molecular shape through orbitals that are energetically accessible for bonding.
Valence bond theory concerns itself with the formation of sigma and pi bonds. Molecular orbital theory is another model for understanding how atoms and electrons are assembled into molecules and polyatomic ions. History[edit] The idea of a correlation between molecular geometry and number of valence electrons (both shared and unshared) was originally proposed in 1939 by Ryutaro Tsuchida in Japan[citation needed], and independently presented in a Bakerian Lecture in 1940 by Nevil Sidgwick and Herbert Powell at the University of Oxford.[4] In 1957 Ronald Gillespie and Ronald Sydney Nyholm at University College London refined this concept to build a more detailed theory capable of choosing between various alternative geometries.[5][6] Description[edit] Chemguide: helping you to understand Chemistry - Main Menu. Introduction. The explosive decomposition of nitrogen triiodide shown in the video is an exciting (and forceful) example of chemistry in action.
For many of us, this explosion is the work of chemists who work magic at the lab bench. In reality, chemistry is much broader. The transformations of matter can be as fast and explosive as the video shows, or involve the slow decay of living organisms into fossil fuels. Wired Chemist.