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Edexcel - Chemistry Unit 2 - 4 June 2013

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Reply 80
Original post by James A
Thanks :biggrin:

Wbu? You in year 12?


Doing AS. Year 11. It was SUCH a pain at first 'cause of the huuuuge jump from IGCSEs! But now Im getting the hang of it :biggrin:


http://en.wikipedia.org/wiki/Sulfur_dioxide

It's definitely two double bonds, sometimes the dot and cross don't add up to the final structure. Check with your teacher when your back at school perhaps?
Original post by Zoeyyy
Doing AS. Year 11. It was SUCH a pain at first 'cause of the huuuuge jump from IGCSEs! But now Im getting the hang of it :biggrin:


iGCSE's eh? You're not a UK student? :smile:
Original post by James A
http://en.wikipedia.org/wiki/Sulfur_dioxide

It's definitely two double bonds, sometimes the dot and cross don't add up to the final structure. Check with your teacher when your back at school perhaps?


Same link you gave, check down, under structure and bonding...
Reply 85
Original post by James A
iGCSE's eh? You're not a UK student? :smile:

Nope, mid east :smile:
Original post by Relaxedexams
Same link you gave, check down, under structure and bonding...


Keyword: Resonance.

The definitive structure is classed as two double bonds, but because it has a resonance, it's classed as two double bonds.
Original post by James A
Keyword: Resonance.

The definitive structure is classed as two double bonds, but because it has a resonance, it's classed as two double bonds.


Right, so is O-S=O wrong, or is it a must to add two double bonds. After all the pi bond is resonant, therefore wouldn't it make more sense if the structure was drawn with one double bond at a time?
Reply 88
Original post by James A
http://en.wikipedia.org/wiki/Sulfur_dioxide

It's definitely two double bonds, sometimes the dot and cross don't add up to the final structure. Check with your teacher when your back at school perhaps?


Ah I thought it might be because of resonance ! :smile:

It's a bit like Ozone... O=O=O

Thanks for the link :smile:
Original post by Relaxedexams
Right, so is O-S=O wrong, or is it a must to add two double bonds. After all the pi bond is resonant, therefore wouldn't it make more sense if the structure was drawn with one double bond at a time?


It's hard to describe, but the molecule alternates in resonance. At one split second, it's O-S=O, the next split second it's O=S-O, therefore, strictly speaking we can't really say the fixed structure is O-S=O, but instead the scientists just assign it as O=S=O. I hope that's a little clearer now.

But when you study unit 5, you will come across benzene and the resonance structure is has.

:yy:
Original post by posthumus
Ah I thought it might be because of resonance ! :smile:

It's a bit like Ozone... O=O=O

Thanks for the link :smile:


Exactly, Ozone has resonance too, good spot !!

:colone:
Reply 91
Oh so NOW it decides to approve my posts from 14 hours ago.. LOL!
Reply 92
Can anyone recommend a good text book for units 4,5 and 6!


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Original post by James A
It's hard to describe, but the molecule alternates in resonance. At one split second, it's O-S=O, the next split second it's O=S-O, therefore, strictly speaking we can't really say the fixed structure is O-S=O, but instead the scientists just assign it as O=S=O. I hope that's a little clearer now.

But when you study unit 5, you will come across benzene and the resonance structure is has.

:yy:


Thanks for clearing it up :smile:
Reply 94
Original post by Relaxedexams
Right, so is O-S=O wrong, or is it a must to add two double bonds. After all the pi bond is resonant, therefore wouldn't it make more sense if the structure was drawn with one double bond at a time?


Check this video tut. It helps a lot.
http://www.youtube.com/watch?v=yxQ2brIlIC0
Reply 97
Original post by NilFBosh
is the fraser book good?


Some people find the facer book easier to understand - some hate it :tongue:

Personally I find it easier to read because I'm used it by now :smile:

It has a lot of unnecessary information in it though! :tongue:
Reply 98


Isnt there a student book? And whats the diff between this and the student book?
Original post by NilFBosh
Isnt there a student book? And whats the diff between this and the student book?


The student book is full of crap. Nothing in it for the exams. "How science works" is the only thing you need to read in it. This book is a better guide.:smile:
....lol big difference.

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