# Is the teacher wrong and I am right?Watch

#1
So, this is a picture of the test and I think the ClF3 answer is right :/, and as you can see on the left I was gonna draw a trigonal bipyramidal but the scribbled it off cause I thought if there is lone pairs so each must've pushed 5 degrees more meaning it will not be a straight line, and btw also the ms says allow any 3 bp and Lp but the teacher is being too stubborn about it probably cause I already got 64/70 and he doesn't want me to get higher lol.
This is AQA June 2010 Chem 1

Markscheme
0
3 years ago
#2
Can't see any of the files you uploaded
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#3
(Original post by langlitz)
Can't see any of the files you uploaded
My bad can you see it now?
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3 years ago
#4
(Original post by akereem100)
My bad can you see it now?
The left one is fundamentally wrong but I'd say that the one on the right should be given the mark
0
#5
(Original post by langlitz)
The left one is fundamentally wrong but I'd say that the one on the right should be given the mark
That's what I thought, thank you
0
3 years ago
#6
(Original post by akereem100)
That's what I thought, thank you
On question 1b for CCl2F2 you have drawn a displayed formula. I think what the question is asking is for you to draw the shape meaning using Wedges, broken lines etc and indicated the lone pairs on there. Reason being this is a Shapes of Molecules Question. But the one on the right is correct. So I can check this can you post a picture of the complete question and the mark scheme for this? Alternatively tell me what exam board and what exam you are doing.
0
3 years ago
#7
(Original post by akereem100)
x
The issue with your structure for ClF3 is that it's not obviously T-shaped; you should have stuck with your first attempt! On the bright side, you will probably not make this mistake again.

The fundamental shape for a five-bond centre is a trigonal bipyramid — three bonds around the middle, one at the top and one at the bottom. Although the markscheme says to award marks for a structure with 3 BPs and 2 LPs, I can understand why your teacher has not credited you. Your diagram looks like a pentagonal planar structure, which is definitely wrong.
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#8
(Original post by BJack)
The fundamental shape for a five-bond centre is a trigonal bipyramid — three bonds around the middle, one at the top and one at the bottom. Although the markscheme says to award marks for a structure with 3 BPs and 2 LPs, I can understand why your teacher has not credited you. Your diagram looks like a pentagonal planar structure, which is definitely wrong.
Yeah that's exactly what he told me today, he did end up giving me the mark though however sadly turns out the 1)a)ii) question is wrong hahahah it has to be Cl2 and F2, oh well thank you everyone
1
3 years ago
#9
(Original post by akereem100)
So, this is a picture of the test and I think the ClF3 answer is right :/, and as you can see on the left I was gonna draw a trigonal bipyramidal but the scribbled it off cause I thought if there is lone pairs so each must've pushed 5 degrees more meaning it will not be a straight line, and btw also the ms says allow any 3 bp and Lp but the teacher is being too stubborn about it probably cause I already got 64/70 and he doesn't want me to get higher lol.
This is AQA June 2010 Chem 1

Markscheme
I would not credit that answer either. You're expected to know the shapes of molecules and yours is not the correct arrangement for 3Bp & 2Lp.
0
3 years ago
#10
Using the AQA mark scheme you would have got both marks
0
3 years ago
#11
(Original post by GDN)
Using the AQA mark scheme you would have got both marks
First one should definitely not get the mark, it shows a fundamental lack of understanding

Posted from TSR Mobile
0
3 years ago
#12
(Original post by JMaydom)
I would not credit that answer either. You're expected to know the shapes of molecules and yours is not the correct arrangement for 3Bp & 2Lp.
EQUATION: 0.5Cl2+1.5F2------> ClF3

remember cl2 and f2 (diatomic molecules)

For shape of ClF3:

Cl is central atom
Using the rules: 7+3=10e =5 pairs hence 3 bp and 2 lp

NOW BE CAREFUL HERE

The lone pairs here have no effect, as the repulsion from one lone pair cancels out the repulsion from the other
hence shape is trigonal planar and bond angle=120
0
3 years ago
#13
(Original post by akereem100)
So, this is a picture of the test and I think the ClF3 answer is right :/, and as you can see on the left I was gonna draw a trigonal bipyramidal but the scribbled it off cause I thought if there is lone pairs so each must've pushed 5 degrees more meaning it will not be a straight line, and btw also the ms says allow any 3 bp and Lp but the teacher is being too stubborn about it probably cause I already got 64/70 and he doesn't want me to get higher lol.
This is AQA June 2010 Chem 1

Markscheme

EQUATION: 0.5Cl2+1.5F2------> ClF3

remember cl2 and f2 (diatomic molecules)

For shape of ClF3:

Cl is central atom
Using the rules: 7+3=10e =5 pairs hence 3 bp and 2 lp

NOW BE CAREFUL HERE

The lone pairs here have no effect, as the repulsion from one lone pair cancels out the repulsion from the other
hence shape is trigonal planar and bond angle=120

good luck!
0
3 years ago
#14
(Original post by akereem100)
So, this is a picture of the test and I think the ClF3 answer is right :/, and as you can see on the left I was gonna draw a trigonal bipyramidal but the scribbled it off cause I thought if there is lone pairs so each must've pushed 5 degrees more meaning it will not be a straight line, and btw also the ms says allow any 3 bp and Lp but the teacher is being too stubborn about it probably cause I already got 64/70 and he doesn't want me to get higher lol.
This is AQA June 2010 Chem 1

Markscheme
Also your teacher is a clear moron- mark scheme awards marks for 3 bond pairs an 2 lone pairs regardless of the shape, as long as you have 3 BOND PAIRS AND 2 LONE PAIRS, you should get the marks regardless of whether the structure exists like that in 3 dimensional space
0
3 years ago
#15
as I said before you would have got both marks for the shapes when applying the mark scheme however you should not have got the mark for the equation since chlorine and fluorine are diatomic
0
3 years ago
#16
(Original post by samcrossley28)
The lone pairs here have no effect, as the repulsion from one lone pair cancels out the repulsion from the other
hence shape is trigonal planar and bond angle=120
This would only be true if the two lone pairs occupied the axial positions, which they don't.
0
3 years ago
#17
(Original post by GDN)
as I said before you would have got both marks for the shapes when applying the mark scheme however you should not have got the mark for the equation since chlorine and fluorine are diatomic
Oh yeah never noticed that, that's bad marking haha

Posted from TSR Mobile
0
3 years ago
#18
A is wrong so take a mark off, the question asks for the molecules, not atoms it's formed from. Plus you should know the diatomic molecules.
0
3 years ago
#19
(Original post by samcrossley28)
EQUATION: 0.5Cl2+1.5F2------> ClF3

remember cl2 and f2 (diatomic molecules)

For shape of ClF3:

Cl is central atom
Using the rules: 7+3=10e =5 pairs hence 3 bp and 2 lp

NOW BE CAREFUL HERE

The lone pairs here have no effect, as the repulsion from one lone pair cancels out the repulsion from the other
hence shape is trigonal planar and bond angle=120
Or..... I could know what I was on about and draw the 'seesaw' shape
0
3 years ago
#20
(Original post by JMaydom)
Or..... I could know what I was on about and draw the 'seesaw' shape
ok then, explain
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