Molecular v Electron Arrangement

[Mia Navarro 1D]

What is the difference between the molecular and electron arrangements? Would you be able to say, for example, that the electron arrangement is tetrahedral, even if the molecular shape is trigonal pyramidal?

[Meredith Steinberg 2E]

Yes, the electron arrangement takes into account the lone pairs (same as looking at the amount of regions of electron density). For example, NH3 has 4 regions of electron density (tetrahedral arrangement), but has a molecular shape of trigonal pyramid.

[Suhail Zaveri]

Hi, so for this question:

Line pairs are counted as bonds in the electron structure so if it is ax2e2 the electron structure is ax4 so tetrahedral. However, molecular is based on shape not actual electron number...hope this helps!