Three of the following molecular models have a tetrahedral central atom, and one does not. Which is the odd one? (There may be a 'hidden' atom directly behind a visible atom in some cases.) (a)

(b)

(c)

(d)

Video transcript

Hey everyone we're told that one out of the four molecular models does not contain a tribunal by pyramidal central atom. If some of the models have a hidden atom behind a visible atom, which one does not contain a tribunal by pyramidal central atom. First let's go ahead and look at a. So we can see right here that we have our central atom A. Which is going to be the black sphere and it's surrounded by five atoms 1234 and five. So those are going to be our light gray spheres. Now three of the five atoms lie on the same plane, which I'm going to draw right here, one at the back and one at the front of the central atom. So it looks like we have that geometry of A X. Five which is in fact tribunal by pyramidal. So answer choice A can't be our answer. Now let's go ahead and look at B. So for B. We have four of the five atoms that surround the central atom lie in one plane. Which is going to be this plane right here and one of the atoms lie on top of the plane. So we do have that possibility of a lone pair at the bottom of the central atom. So it looks like this will be a. X. Five E. One which we've learned to be square pyramidal. So it looks like answer choice B. Might be our answer but let's go ahead and assess C. N. D. Looking at sea, we have that central atom and it's surrounded by five atoms which are light gray spheres. Three of the five atoms lie in the same plane so two of the five atoms are parallel to each other and lie opposite of that plane. So it looks like our geometry here is going to be a X. Five which we said was tribunal by pyramidal which tells us that C. Can't be our answer. Now let's go ahead and look at answer choice D. So for D. Again we have that central atom and it's surrounded by five atoms. Three of the five atoms lie on the same plane and two of the five atoms are parallel to one another and lie opposite of the plane. So similar to answer choice C. This has a geometry of A X. Five which again is tribunal by pyramidal. So answer choice D. Can't be your answer as well. So it looks like we were correct in stating that answer choice B. Is going to be our answer. Now I hope that made sense. And let us know if you have any questions