lone pairs

[Lauren Bui 1E]

why do lone pairs have to be across from each other if there are multiple?

[Shanzey]

I believe that we put the lone pairs across from each other in order to minimize electron repulsion for octahedral shapes. For instance, Dr. Lavelle used the example of XeF4 in lecture and placed the lone pairs opposite from each other because that is the shape with the least amount of repulsion for that octahedral shape.

[Katheryne N 3G]

In the case of a molecule such as XeF4 (Xenon Tetrafluoride) that has 6 regions of electron density, including 2 lone pairs on Xe and 4 F atoms bonded to Xe, you want a shape of the molecule that would result in the least amount of repulsion between the higher regions of electron density and so the lone pairs would need to be as far away from each other as possible. In the case of this molecule, it would be on opposite sides of the central atom.

[Ayushi2011]

Lone pair-lone pair electron repulsion is the highest, so they need to be placed away from each other as we want minimum repulsion for most stability.