write the posulates of VSEPR theory
5 mark
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The postulates of the VSEPR theory are listed below
In polyatomic molecules (i.e. molecules made up of three or more atoms), one of the constituent atoms is identified as the central atom to which all other atoms belonging to the molecule are linked.The total number of valence shell electron pairs decides the shape of the molecule.The electron pairs have a tendency to orient themselves in a way that minimizes the electron-electron repulsion between them and maximizes the distance between them.The valence shell can be thought of as a sphere wherein the electron pairs are localized on the surface in such a way that the distance between them is maximized.Should the central atom of the molecule be surrounded by bond pairs of electrons, then, the asymmetrically shaped molecule can be expected.Should the central atom be surrounded by both lone pairs and bond pairs of electrons, the molecule would tend to have a distorted shape.The VSEPR theory can be applied to each resonance structure of a molecule.The strength of the repulsion is strongest in two lone pairs and weakest in two bond pairs.If electron pairs around the central atom are closer to each other, they will repel each other. This results in an increase in the energy of the molecules.If the electron pairs lie far from each other, the repulsions between them will be less and eventually, the energy of the molecule will be low