However, the tetrahedral geometry is a better alignment since the angle between the groups is 109.5 o:Įach of these geometries that we have discussed has a name: If you have never heard about the tetrahedral geometry and thought it was 90 o, that is fine, we all did when first introduced to this topic. What do you think it is when there are four atoms connected to the center? When there are three atoms around the central unit, the optimal angle is 120 o:
In this case, putting them across at 180 o allows for achieving the optimal geometry: An orientation that puts them as far away as possible with the same angle between all.
Keeping in mind that the blue atoms repel each other, propose an optimal geometry for them. The red sphere represents the central atom and the blue ones are connected to it:
Let’s use this model examples to illustrate how this works. It is the keyword and all you need to grasp this concept is keeping in mind the idea that atoms want to stay as far apart from each other as possible because of the repulsion between the electrons on them. First, what does VSEPR stand for? It is the Valence Shell Electron Pair Repulsion theory. In today’s post, we will discuss the VSEPR theory which helps us understand the geometry of molecules.
