[krisshP]

I'm confused about the structure of ethene.

On an AQA mark sheme ethene's structure is exactly like the following:
http://www.bbc.co.uk/scotland/learni...ges/ethene.gif

However in a CGP revision guide ethene's structure is like the following:
http://0.tqn.com/d/chemistry/1/0/L/G/1/ethylene.jpg

I'm not so sure about which one is the right one. In the question paper for the mark scheme I drew the ethene structure which is on the CGP guide. However the AQA mark scheme structure is slightly different due to the position of the 4 Hydrogen atoms.

My question is which structure is the correct true structure of ethene?

[EierVonSatan]

They're both just cartoons Both are fine in terms of structure, just the CGP version more accurately represents the shape (i.e. the bond angles)

[krisshP]

(Original post by EierVonSatan)
They're both just cartoons Both are fine in terms of structure, just the CGP version more accurately represents the shape (i.e. the bond angles)

Thanks for helping me. I was confused on whether I should give myself the mark for the question or not.

[Username_valid]

Well technically the CGP revision guide is correct as the carbon atoms have 3 areas of electron densities so it's a trigonal planar shape with the bond angle being 120 degrees. However when they ask you to draw the structure then probably both are correct if that's what it says in the mark scheme.

[thegodofgod]

(Original post by krisshP)
I'm confused about the structure of ethene.

On an AQA mark sheme ethene's structure is exactly like the following:
http://www.bbc.co.uk/scotland/learni...ges/ethene.gif

However in a CGP revision guide ethene's structure is like the following:
http://0.tqn.com/d/chemistry/1/0/L/G/1/ethylene.jpg

I'm not so sure about which one is the right one. In the question paper for the mark scheme I drew the ethene structure which is on the CGP guide. However the AQA mark scheme structure is slightly different due to the position of the 4 Hydrogen atoms.

My question is which structure is the correct true structure of ethene?

Well I think it depends as to whether you should give yourself the mark; if you're doing GCSEs (or equivalent), give yourself the mark, however if you're doing A levels (or equivalent), don't give yourself the mark.

If you haven't yet learned about bond angles, give yourself the mark

[EierVonSatan]

(Original post by thegodofgod)
Well I think it depends as to whether you should give yourself the mark; if you're doing GCSEs (or equivalent), give yourself the mark, however if you're doing A levels (or equivalent), don't give yourself the mark.

If you haven't yet learned about bond angles, give yourself the mark

So if a question asked you to draw ethane and you drew...



you shouldn't get the mark?

[thegodofgod]

(Original post by EierVonSatan)
So if a question asked you to draw ethane and you drew...



you shouldn't get the mark?

I think it would depend on the context of the question then - if the question's about bond angles, you should really draw the shape with the wedged / dotted lines.

I remember a question about drawing the structures (showing bond angles) of two optical isomers back in Unit 4 (A2), and they only gave the mark if you drew the wedged / dotted lines + showed the mirror line.

[EierVonSatan]

(Original post by thegodofgod)
I think it would depend on the context of the question then - if the question's about bond angles, you should really draw the shape with the wedged / dotted lines.

I remember a question about drawing the structures (showing bond angles) of two optical isomers back in Unit 4 (A2), and they only gave the mark if you drew the wedged / dotted lines + showed the mirror line.

Indeed, context is key

[thegodofgod]

(Original post by EierVonSatan)
Indeed, context is key

But I think if they specifically stated to draw the displayed formula of ethene, you should get the mark for

[The Doggfather]

They are both correct

Another way of drawing ethene is the skeletal structure below;

=

[krisshP]

Thanks

[mattparker]

The first picture shows ethene ready for electrophilic attack


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