3
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Here's a "simple" bond diagram of 1,1,1,2-Tetrafluoroethane which I believe is a Lewis structure:

1,1,1,2-Tetrafluoroethane

OK, that's easy enough - four bonds from each carbon atom, and each fluorine atom having one bond.

Here are some more "complicated" bonds which I have yet to do in my high school chemistry class, so I don't understand how to interpret them.

Here's caffeine:

Caffeine Caffeine

And chloroform:

Chloroform Chloroform

How would I go on interpreting these diagrams? Or is there missing information?

Image sources: Wikimedia

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  • $\begingroup$ There are many different ways of representing molecular structures, see the Wikipedia page on structural formula(e) for a summary. The one used most frequently by organic chemists is a skeletal formula (often referred to as a "bond-line structure" or "line-angle formula"), which is what you see in that representation of caffeine. $\endgroup$ – Greg E. Jul 19 '14 at 22:08
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The second structure you posted is a line angle diagram. In this diagram, methyl groups (-CH3) are implied using sticks with nothing at the end.

enter image description here

Carbon atoms are also implied; carbons exist at every "corner" of the polygon which doesn't have an element explicitly identified. Hydrogens attached to carbons are also implied. So at the intersection of two lines, if there are no other attachments and no charge, you can expect there to be two hydrogens (carbon is generally tetravalent).

enter image description here

The third structure you posted is a wedge-dash diagram. Wedges depict substituents angled toward you; dashes are substituents pointing away from you; the lines are coplanar. The advantage of this diagram is that it shows the 3D nature of the molecule. Your first picture of the fluoro-carbon compound implies 90 degree bond angles. However, you should realize that the carbon atoms are sp3 hybridized and thus should not have 90 degree bond angles.

enter image description here

enter image description here

Further reading and exploration of other depictions of molecular structure:

http://www.masterorganicchemistry.com/2010/10/15/the-many-many-ways-to-draw-butane/

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  • $\begingroup$ Thanks for the detailed explanation! Can we always assume that a stick with nothing at the end implies $CH_3$? Also, what compound is in the first image you posted? $\endgroup$ – baharini Jul 19 '14 at 22:16
  • $\begingroup$ Yes. That's always true. The compound in the first image is 2-butene. The "ene" ending implies the presence of a double-bond (alkenes are hydrocarbons with double bonds); the 2 identifies the location of the double bond (the double bond starts on carbon number 2). $\endgroup$ – Dissenter Jul 19 '14 at 22:35

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