VSEPR(Valence Shell Electron Pair Repulsion) Theory
Have you ever wanted to get as far away from your siblings as possible? Imagine that you are in a room, with your parents at the center. You would have to get as far away from your brother, while having you and your brother maintain equal distances from your parents. How would you do it?
The easiest way to do it would be to form a line between you and your parents, and put your brother 180 degrees away from that line, forming one long line. Now what if you had 2 brothers? What shape would you form so all 3 siblings maintained maximum distance from each other, but were still the same distance away from your parents? You’d form a triangle, and the angle between each sibling and parent line would be 120 degrees.
Here's a helpful chart of various electron geometries : http://liakatas.org/chemblog/wp-content/uploads/2008/07/vsepr.png
1. Now imagine that you have 3, 4, or 5 siblings. What formation would you create to maximize distance between all of them? Keep in mind that you can 3d space.
2. What would the angles be between each of the parent sibling lines be?
3. How does this sibling example relate to molecular geometry?