Central elements with five electron groups can have zero to 3 lone pairs to give four possible molecular geometries. So we can have 0, 1, 2, or three lone pairs on our central element. So here we have 5 electron groups and the way it can break down is we have 5 surrounding elements or bonding groups and 0 lone pairs on the central element. Or it could be 4 to 1 or it could be three to two or finally it can be two to three.
Now here if we take a look, we have examples. Here we have phosphorus pentachloride, here we have selenium tetrafluoride, here we have bromine, bromine, tri iodide and here we have xenon dichloride as examples. Now their visualizations here, if we take a look visually this would look like 2 pyramids that are stacked on top of each other. And if we think about it's 2-3 legged pyramids stacked on top of each other, its molecular geometry name would be trigonal because each pyramid has three legs and there's two pyramids on top of each other by pyramidal.
For the next one, if we have 4 surrounding elements and 1 lone pair on the central element, it would visually look like this here. I've added a person here and a person here to help us think of what this would look like in a daily object. So if you look at it, it kind of looks like a seesaw. So that's the name. Seesaw.
For the next one, if you have 3 surrounding elements and two lone pairs on your central element, this here looks like the letter T, so that's why we call it T shaped. And then finally, if you have two surrounding elements and three lone pairs on your central element, you look linear, look like a straight line. So these would be our different possible molecular geometries if we have 5 electron groups involved in our molecule.
All right, so keep them in mind and just remember visually what they look like. That's a great way to help you remember their name.