MM2002
Badges: 9
Rep:
?
#1
Report Thread starter 1 year ago
#1
What are the bond angles for BrF3?
I am aware there are 3 bonding pairs and 2 lone pairs so the structure is based of a triangular bipyramidal. As there are two lone pairs is the bond angle going to be 85 and 115?
0
reply
Pigster
Badges: 20
Rep:
?
#2
Report 1 year ago
#2
(Original post by MM2002)
What are the bond angles for BrF3?
I am aware there are 3 bonding pairs and 2 lone pairs so the structure is based of a triangular bipyramidal. As there are two lone pairs is the bond angle going to be 85 and 115?
When there are 5bp, you get two bonds on the axis and three on the equator.

When there are 3bp and 2lp, where will the 2lp position themselves? i.e on the axis and/or on the equator?
1
reply
username4339332
Badges: 15
Rep:
?
#3
Report 1 year ago
#3
(Original post by MM2002)
What are the bond angles for BrF3?
I am aware there are 3 bonding pairs and 2 lone pairs so the structure is based of a triangular bipyramidal. As there are two lone pairs is the bond angle going to be 85 and 115?
No. This is an exception to the rule. You're correct in saying that the shape is based on trigonol bipyramidal due to there being 5 electron pairs however, the shape is just trigonol planer as you'll soon find out why. The image below shows the general shape of a trigonal bipyramidal molecule. Knowing that it has 2 lone pairs, these lone pairs will repel the most, and therefore will want to be as far as possible in the molecule to create the largest bond angle. One of the lone pairs will be at the top of the molecule in the same plane, and one at the bottom in the same plane as this creates the largest bond angle and distance apart. This means there is no net repulsion, since the repulsion from lone pair at the top of the molecule cancels out the repulsion from the bottom, leaving a normal trigonal-planer shaped molecule. The bond angle is therefore 120 degrees as the bonding pairs don't undergo a net repulsion
https://p7.hiclipart.com/preview/623...try-others.jpg
Last edited by username4339332; 1 year ago
0
reply
Pigster
Badges: 20
Rep:
?
#4
Report 1 year ago
#4
(Original post by Huckipity)
the shape is just trigonol planer as you'll soon find out why.
Are you saying Wikipedia is wrong?

https://en.wikipedia.org/wiki/Bromine_trifluoride

How dare you?
0
reply
Queenbee1323
Badges: 13
Rep:
?
#5
Report 1 year ago
#5
It would be 87.5, from what I'm reading from my notes
0
reply
MM2002
Badges: 9
Rep:
?
#6
Report Thread starter 1 year ago
#6
(Original post by Huckipity)
No. This is an exception to the rule. You're correct in saying that the shape is based on trigonol bipyramidal due to there being 5 electron pairs however, the shape is just trigonol planer as you'll soon find out why. The image below shows the general shape of a trigonal bipyramidal molecule. Knowing that it has 2 lone pairs, these lone pairs will repel the most, and therefore will want to be as far as possible in the molecule to create the largest bond angle. One of the lone pairs will be at the top of the molecule in the same plane, and one at the bottom in the same plane as this creates the largest bond angle and distance apart. This means there is no net repulsion, since the repulsion from lone pair at the top of the molecule cancels out the repulsion from the bottom, leaving a normal trigonal-planer shaped molecule. The bond angle is therefore 120 degrees as the bonding pairs don't undergo a net repulsion
https://p7.hiclipart.com/preview/623...try-others.jpg
Thank you
0
reply
username4339332
Badges: 15
Rep:
?
#7
Report 1 year ago
#7
(Original post by sakthar23)
It would be 87.5, from what I'm reading from my notes
(Original post by Pigster)
Are you saying Wikipedia is wrong?

https://en.wikipedia.org/wiki/Bromine_trifluoride

How dare you?
My teacher did a molecule with the exact same number of lone pairs and bonding pairs as the one here and said it will be trigonal planer for the reasons I explained. :confused:
0
reply
Pigster
Badges: 20
Rep:
?
#8
Report 1 year ago
#8
(Original post by Huckipity)
My teacher did a molecule with the exact same number of lone pairs and bonding pairs as the one here and said it will be trigonal planer for the reasons I explained. :confused:
Teachers can get stuff wrong.

If you check an AQA MS (which I bet the OP is studying), then they allow either trigonal planar or T-shaped.
0
reply
username4339332
Badges: 15
Rep:
?
#9
Report 1 year ago
#9
(Original post by Pigster)
Teachers can get stuff wrong.

If you check an AQA MS (which I bet the OP is studying), then they allow either trigonal planar or T-shaped.
So my teacher was right...
1
reply
Pigster
Badges: 20
Rep:
?
#10
Report 1 year ago
#10
(Original post by Huckipity)
So my teacher was right...
BrF3 is T-shaped. It just is. What the exam board will accept and what is correct are not necessarily the same thing.
0
reply
username4339332
Badges: 15
Rep:
?
#11
Report 1 year ago
#11
(Original post by Pigster)
BrF3 is T-shaped. It just is. What the exam board will accept and what is correct are not necessarily the same thing.
No, the geometry of the molecule is T-shaped - I agree with you on that as geometry takes into account the bonding pairs and lone pairs positions in the molecule. However, I am also correct in saying the shape is trigonal planer, hence why the mark scheme accepts it. Shape just takes into account bonding pairs and excludes lone pairs - which is all we need for A level Chemistry. So it is correct in saying the shape trigonal planer, however its a simplification in the real world. Geometry makes it more complicated and only matters if you want to go on to do a chemistry degree since it's not in the spec for AQA.
0
reply
username4339332
Badges: 15
Rep:
?
#12
Report 1 year ago
#12
(Original post by Pigster)
Are you saying Wikipedia is wrong?

https://en.wikipedia.org/wiki/Bromine_trifluoride

How dare you?
Also, Wiki isn't always right as it can be edited by anyone :P
0
reply
X

Quick Reply

Attached files
Write a reply...
Reply
new posts
Back
to top
Latest
My Feed

See more of what you like on
The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

Personalise

Do you think receiving Teacher Assessed Grades will impact your future?

I'm worried it will negatively impact me getting into university/college (74)
38.14%
I'm worried that I’m not academically prepared for the next stage in my educational journey (19)
9.79%
I'm worried it will impact my future career (12)
6.19%
I'm worried that my grades will be seen as ‘lesser’ because I didn’t take exams (48)
24.74%
I don’t think that receiving these grades will impact my future (25)
12.89%
I think that receiving these grades will affect me in another way (let us know in the discussion!) (16)
8.25%

Watched Threads

View All
Latest
My Feed