VSEPR questions, angles

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joonkimdds

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1) what's the difference between V shaped and bent?
I think they are the same but my note says V shaped is <120 and bent is <109.5 degree

from trigonal planar, if one of the X is electron pairs, that's bent.
trigonal planar is 120 degree. Since electrons take more spaces, I thought it's safe to say it's <120 but the note says <109.5. hm....

2)seesaw is >90
shouldn't it be smaller than 90 since electrons pairs at the top take more spaces and push them down?

trigonal bipyramid had 90 degree. When one of the X atom from the T shaped structure of trigonal bipyramid is electron pairs, it becomes seesaw. Since electron pairs take more spaces than regular X atom, it should push the other two of the T shape down. When these two are pushed down, the angle between these and 2 legs should be less than 90.

3) square pyramid is >90
I think it should be smaller than 90 for the same reason I described above.
128px-AX5E1-2D.png

E is electron pairs. Since it takes more spaces than X at the top, all the other 4 X on the side should go toward top and so the angle between these 4 and the X at the top should be less than 90 in my opinion.
 
1. My guess is one of the two has the trigonal planar electron domain geometry, and one has tetrahedral ED geometry, but i have never heard of V shaped and it's not in my book.

2. Not sure, could be because there are more atoms in the structure?

3. I'm very confident that this is the result of the interactions with the other 5 atoms. if you push the x's up to a angle greater than 90, then there is going to be a lot of resistance because of the X at the top interacting with all four X's. The electron pair might be pushing them down, but the geometry is supposed to minimize the interaction. Regardless I don't think you will have to worry, if it says greater than 90 in the book then it should work on the test
 
Thanks Ozzie.

I think I understand 2, and 3 now~!

I think 2 and 3 have the same reason.

But I still gotta find out what V shape is.
 
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