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How many carbons are in this skeletal structure? I was told to draw a circle at the start of the structure and at each point the line turns off to get the total number of carbons but doing so would result in 6 carbons which I know is wrong but why is it wrong? And where on the structure are the carbons located?

Thanks for clearing this up for me!

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  • $\begingroup$ OK, you've described a procedure and immediately told us that it is wrong. How do you know it is wrong? $\endgroup$ Nov 29 '17 at 17:59
  • $\begingroup$ Because 6 carbons just looks too many for the size of the structure in my opinion. $\endgroup$
    – user55394
    Nov 29 '17 at 18:04
  • $\begingroup$ What a weird way of counting the carbons. Just convert all the points where the lines join into a "C", then you should see how many you have. $\endgroup$
    – gilleain
    Nov 29 '17 at 18:06
  • $\begingroup$ So as such this structure should have 3 carbons? $\endgroup$
    – user55394
    Nov 29 '17 at 18:09
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    $\begingroup$ Sorry, I wasn't clear - this is in addition to the ones that are already shown as "C". What is going on here is that 'terminal' carbons (at the end of a chain) can optionally be shown as element symbols (CH3) - you could equally convert these ones to points, and get just a line drawing. $\endgroup$
    – gilleain
    Nov 29 '17 at 18:18
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Your intuition is not wrong.

There are indeed 6 carbon atoms in the molecule (3-methyl-pentane).

With bondline/skeletal notation, there's a carbon atom at all the vertices; at the ends, and every time the line changes direction.

Counting the carbon atoms then becomes as simple as counting the vertices.

This becomes more apparent if you explicitly write all the atoms like illustrated below:

3-methyl-pentane

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