Xenon molecular shapes

Three common molecular shapes are associated with octahedral electron group geomehy. Most often, an inner atom with a steric number of 6 has octahedral molecular shape with no lone pairs. Example uses a compound of xenon, whose chemical behavior is described in the Chemical Milestones Box, to show a second common molecular shape, square planar. 

Follow the usual procedure. Determine the Lewis stmcture, then use it to find the steric number for xenon and to deduce electron group geometry. Next, use the number of ligands to identify the molecular shape. 

Xenon tetraflnoride reacts with antimony pentafluoride to form the ionic complex [XeF3]+[SbFg]. (a) Which depiction shows the molecular shapes of the reactants and product (b) How, if at aU, does the hybridization of xenon change in the reaction ... 

The valence shell of the xenon atom contains 12 electrons eight from the xenon and one each from the four chlorine atoms. There are four bonding pairs and two lone pairs. The basic shape adopted by the molecule Is octahedral. Flowever, there are two possible arrangements for the lone pairs. The first structure, square planar, minimizes the repulsion (the lone pairs are at 180° to each other) and Is hence adopted as the molecular shape (Figure 14.7). As a general rule, for a molecule where the electron domains adopt an octahedral structure, any lone pairs will occupy positions opposite to one another. 

Early molecular dynamics simulations focused on spherically shaped particles in zeolites. These particles were either noble gases, such as argon, krypton, and xenon, or small molecules like methane. For these simulations, the sorbates were treated as soft spheres interacting with the zeolite lattice via a Lennard-Jones potential. Usually the aluminum and silicon atoms in the framework were considered to be shielded by the surrounding oxygen atoms, and no aluminum and silicon interactions with the sorbates were included. The majority of those studies have concentrated on commercially important zeolites such as zeolites A and Y and silicalite (all-silica ZSM-5), for which there is a wealth of experimental information for comparison with computed properties. 

Molecules of noble gas compounds have shapes in excellent agreement with VSEPR theory, although to form two-electron bonds, xenon must promote valence electrons to higher-energy orbitals such as 5d. This model can be avoided by a molecular orbital treatment which, in Xep2, forms three-centre bonds from xenon 5p and fluorine 2p orbitals. The Xe—F bonds then have an order much less than one. The experimentally determined bond lengths are in better agreement with the two-electron, two-centre bonds of VSEPR theory. 

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