The Gillespie model (VESPR model) is an empirical and very simple method that permits to determine the type of geometrical structure of a given molecule: The "groups" are counted: - First search for the central atom. - Then write the Lewis structure ( don't forget the lone pairs ): - Every atom attached to the central atom by single, double or triple bond counts for one "group" - Every lone pair counts for one "group" Then determine the structure by the number of "groups": 2 linear 3 trigonal planar 4 tetrahedral 5 trigonal bipyramidal 6 octahedral
