Bond Angle of Molecule

[Charlene D 3H]

Hi for one of the sapling problems, it asks for the smallest bond angle in a molecule with two bonds and two lone pairs. In my notes (which could be wrong) and for my answer I wrote 104.5 degrees and got it correct, but the solution explanation uses approximately or slightly less than 109.5 degrees.

Did I get the answer correct because Sapling allows answers within a certain margin?
If I am given a similar question in the future, should I just use 109.5 degrees as my answer?
Thank you!

[Edward Tang 1k]

Well 104.5 is "approximately or slightly less than 109.5" so you're correct in your answer. I believe answers for bond angles are always accepted with in a range of possible angles unless it's for obvious ones like 90, 109.5, 120, or 180.

[Sophia Kalanski 1A]

I think that its fine to list an answer that falls in the correct margin of the answer. In this case, since we knew that there were 4 bonds, and 2 of them were lone pairs, they would cause the angle between the lone pairs to be greater than 109.5 and the angles between the lone pairs and bonding pairs to be greater as well so from that we would know that the bonding angle between the 2 bonding pairs would have to be less than 109.5 degrees and putting (mostly) any answer that satisfies that would work.

[RitaThomas_3G]

As stated by the answers above, I believe 104.5 would be within the range of answers possible. Maybe just make sure to say it is approximately that angle to show that it could be slightly more or less that number.

[Joshua Swift]

When lone pairs are present in the VSEPR model, it often uses for the approximation of less than 109.5 degrees. Since you got the angle correct, you were correct, but we technically don't need to know the exact angle, just that it is less than 109.5 degrees.

[Charlotte Adams 1A]

We know it would be less than 109.5 because that is the bond angle if all the atoms are the same, but since the atoms differ, we know that some atoms will be pushed closer together and have a smaller bond angle that we would have to determine experimentally. We would not be able to look at the shape and tell the exact bond angle.

[Keshav Patel 14B 2B]

You got the answer correct because you chose the experimental value of the degrees when you have 2 lone pairs and 2 bonds. So both answers were acceptable.

[Emily Jacobo 1C]

I had a question about this too! thanks to all responded, it makes sense now