How does a trigonal pyramid differ from a tetrahedron so far
as ...

Question

How does a trigonal pyramid differ from a tetrahedron so far 
as molecular geometry is concerned?

Accepted Answer

welcome back everyone in this example we're asked what is the difference between triggered all by pyramidal and seesaw based on molecular geometry. So we want to recall the following notation being a X. And then E notation where X will have a subscript. That is a whole number representing the atoms our central atom of a molecule is bonded to. And we will also have a number that is a whole number subscript that represents our number of electrons, specifically lone pair electrons. So we'll say loan electrons on our central atom. So X. Again, this number of atoms bonded to a central atom in a molecule. And so we should recall that for tribunal by pyramidal molecular geometry That will correspond to AX five as our notation. So this is the tribunal by pyramidal molecular geometry of our molecule. And this corresponds to thus five electrons or sorry, five atoms bonded to our central atom. And we're comparing this to our seesaw notation. So just to make more room, we have seesaw notation, which we should recall corresponds to a X four E notation. So this is for seesaw molecular geometry and we should recognize that thus this means we have four atoms bonded to our central atom and we have one lone pair on our central atom. So we just have E, which ultimately means one electron pair on the central atom. We don't really need to write that subscript of one there. So looking at the answer choices, we can see that statement A says that Tribunal by pyramidal has five groups. We agreed that X is specifically referring to atoms bonded to the central atom. And groups would also entail not only atoms but electron groups. So we can automatically rule out choice A. Because again groups would entail atoms plus lone pairs moving onto Choice B. It says that the original by pyramidal has five atoms attached to the central atom. We can agree with that while seesaw only has four. Or sorry? Yes. Looking at see Saw we have the subscript of four. And looking at our subscript of tribunal by pyramidal we have that subscript of five for five atoms and then four atoms for seesaw. So actually we can completely agree with Choice B. It's a true statement. And so we can see that as a good prospect for a final answer. But moving on to choice see it says a trickle by pyramidal has one lone pair attached to the central atom. So do we have an invitation in here for two? Original by pyramidal? No we don't. So we can automatically rule out choice C. Because this is not true, It has zero lone pairs. And then Choice D. Says that trickle by pyramidal has two lone pairs. We can also automatically rule out choice D. This is not true. So the only true statement was Choice B. Meaning that choice B is our final answer which reads that trickle by pyramidal has five atoms meaning it has a X five notation attached to the central atom while seesaw only has four, which is why it has a X four E one notation. So if you have any questions, please leave them down below. I hope everything I went through is clear and I'll see everyone in the next practice video.

Watch next