Vesper theory

Molecular geometry is the general shape of a molecule as determined by the relative positions of the various atomic nuclei. A number of physical properties such as melting point, boiling point, density and a number of chemical properties are based on the molecular geometry. A very useful model to predict the general shape of a molecule was developed by Gillespie and Nyholm in 1957. The theory called the Valence Shell Electron Pair Repulsion (VSEPR pronounced as vesper) theory is an... 

The shapes of molecules are determined by actual experiments, not by theoretical considerations. But we do not want to have to memorize the shape of each molecule. Instead, we would like to be able to look at a Lewis structure and predict the shape of the molecule. Several models enable us to do this. One of the easiest to use is valence shell electron pair repulsion theory, which is often referred to by its acronym VSEPR (pronounced vesper ). As the name implies, the theory states that pairs of electrons in the valence shell repel each other and try to stay as far apart as possible. You probably remember this theory from your general chemistry class. The parts of VSEPR theory that... 

Pairs of electrons, childish as they are, behave in a similar manner — those negative charges want to be as fcir apart as possible. The valence shell electron pair repulsion (VSEPR) theory is used to predict the shapes of molecules based on the idea that similarly charged electron pairs want to be as far apart from one another as possible. Though it looks like V-S-E-P-R, the theory name is most commonly pronounced vesper. ... 

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