Question

How do you determine the molecular geometry of the molecule `BeCl_2`?

Answer 1

Apply, VESPER.......and we get a linear `BeCl_2` molecule.

Explanation:

How many valence electron pairs surround the central beryllium atom? Beryllium forms 2 electron pairs to make `2xxBe-Cl` bonds. VESPER suggests that the electron pairs are arranged in a way that MINIMIZES their interaction, and thus `/_Cl-Be-Cl=180^@`; the molecule is therefore LINEAR.

Around each chlorine atom there are 4 electron pairs (the 7 native Cl electrons), and the one from beryllium involved in the `Be-Cl` bond. These electron pairs are arranged in a tetrahedral geometry, but because these are non-bonding lone pairs, here they do not influence geometry.