Square Pyramidal (AX5E)

This is an example of a square pyramidal molecule. There are five atoms surrounding a central atom with a lone pair of electrons. The outer atom that is at the very top of the molecule is in the "apical position." The four surrounding atoms that are at the base of the molecule are known as the "basal atoms," and the lone pair exists on the central atom. The apical A-X bond distance is always shorter than the basal-central bond distances. The apical-center-basal angle is much different from molecule to molecule. In the molecule BF5, the central atom is actually lower than the basal plane, so the square pyramidal molecule does not always have the exact shape shown to the left. In the case of BF5, the reason that the central atom is pushed down is because of electron repulsion from the lone pair.

To zoom, hold "Shift", and hold the left mouse button moving it across the image. To rotate the molecule manually, hold the left mouse button and drag it across the picture.




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