Part A. Use the Model mode in the simulation to identify the geometries for ozone, phosphate ion, and argon fluorohydride (for which the Lewis structures are depicted, and the resonance forms can be ignored).
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The shapes of molecules depend on the number of electron groups that surround a central atom. For molecules in which all electrons around the central atom are participating in bonding, the molecular geometry is the same as the electron geometry, and the molecular shapes are linear, trigonal planar, tetrahedral, trigonal bipyramidal, and octahedral. However, nonbonded electrons, which wouldn't be observed in the molecular geometry, affect the overall distribution of electron groups; therefore, the molecular and electron geometries will be different when nonbonding electrons are present.
This can be exemplified in the case of ammonia, NH3. Ammonia has three bonding groups, but it will not exhibit trigonal planar geometry because the lone pair of electrons exerts a repulsive force. There are four electron groups (three bonding groups and one nonbonding group) in ammonia, which means that the electron geometry will be tetrahedral. When only the molecular structure is examined, the lone pair is not seen, and the molecular geometry will adopt a more pyramidal structure that can be seen in the image below (trigonal pyramidal).
The valence-shell electron-pair repulsion (VSEPR) model encompasses the geometries that result from the various interactions that occur between electron groups (also called electron domains) and the relative repulsive forces exerted by each type of electron group (lone pair, single bond, double bond, and triple bond). VSEPR models also predict both the electron and molecular geometries, but not all reference charts may indicate bond angles.
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