CHEMISTRY COMMUNITY

I think I have a general understanding but what are the specific differences between molecular shape and electron configuration. Why do we even bother with the molecular shape? What are their respective significances?

Electron configuration is the arrangement of the electrons in a molecule. However, the molecular shape doesn't necessarily follow the electron configuration (though it is influenced by it). For example, a molecule could have a tetrahedral electron configuration but if it has a lone pair, that means the molecular shape would be trigonal pyramidal.

Electron geometry describes the arrangement of electron groups. Molecular geometry describes the arrangement of atoms, excluding lone pairs.

I like to think of arrangement and shape as two separate things, where the shape is determined by the geometry and the arrangement is depended on electrons, which includes the electron configuration.

Molecular shape is the shape we get while looking mostly at the bonds (I say 'mostly' because lone pairs do affect molecular shape), while electronic geometry considers both bonds and lone pairs in the shape. Thus, electronic geometry only has the basic shapes (ie tetrahedral, trigonal bipyramidal, octahedral), while molecular shape gives us some of the weirder shapes (ie seesaw, bent, T-shaped) because of the influence of lone pairs. I'd say that we tend to pay more attention to molecular shape, because that can tell us more about the properties of the molecule.