Molecular Shape of BF3: Trigonal Planar or Pyramidal?

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SUMMARY

The molecular shape of BF3 is definitively trigonal planar, as confirmed by its geometry and symmetry. The discussion clarifies that while BF3 is nonpolar, the molecule BY3 can exhibit different shapes, including trigonal pyramidal or T-shaped, depending on the identity of Y. The confusion arises from the phrasing "confirms the polarity," which should be interpreted as confirming that BY3 is a polar molecule. The distinction between the shapes of BF3 and BY3 is crucial for understanding molecular polarity.

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Homework Statement
Experiment confirms the polarity of the molecule of formula BY3. Which molecular shapes are possible and which impossible for BY3?
Relevant Equations
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Answer given is " The molecule could be trigonal pyramidal or T shaped, but could not be trigonal planar."

I am confused as the shape of BF3 is trigonal planar...
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I suppose Y in the BY3 is intended to mean "some particular element", not "every possible element". In other words, question asks about possible shape of a specific molecule for which we know it is polar, not for a shape of every existing molecule - as not all of them will be identical (some will be polar, some will be not polar).
 
daphnelee-mh said:
Homework Statement:: Experiment confirms the polarity of the molecule of formula BY3. Which molecular shapes are possible and which impossible for BY3?
Homework Equations:: -

Answer given is " The molecule could be trigonal pyramidal or T shaped, but could not be trigonal planar."

I am confused as the shape of BF3 is trigonal planar...

Maybe they mean trigonal planar is not polar in the way BY3 is when B is not in the same plane as the Y's?
 
Last edited:
It is hard to know exactly what Y represents. Is there part of the problem statement not shown in the question?
 
No, just written as this
 
daphnelee-mh said:
Experiment confirms the polarity of the molecule of formula BY3.
snip
I am confused as the shape of BF3 is trigonal planar...
Is BF3 polar?
 
Nonpolar, maybe I misunderstood the meaning, as I thought " confirms the polarity " may be polar or nonpolar
 
I can guarantee you that Y means "unspecified element" as others have mentioned.

"Confirms the polarity..." is actually poor wording. You should read it as "confirms it is a polar molecule".
 

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