Lily asked in Science & MathematicsChemistry · 8 months ago

How to name organic compounds from a molecular formula?

For instance, take C3H8. How would you draw and name this molecule? (I know it can take more than one structure, but just stick to simple stuff)

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  • 8 months ago

    The names of the first four hydrocarbons are methane, ethane, propane, and butane. One way to remember this is to say Me eat peanut butter. The first letter of each of these words is the first letter of the names of first letter of the first four hydrocarbons.

    The name of C3H8 is propane, because it has three carbon atoms. The name of CH4 is methane, because it has one atom. The name of C4H10 is butane, because it has four carbon atoms. Each of these compounds has single bonds. If you go to the following website, you will the straight line formulas of the first four hydrocarbons.

    http://hyperphysics.phy-astr.gsu.edu/hbase/Organic...

    If you go to the following website, you will see the two isotopes of butane

    http://hyperphysics.phy-astr.gsu.edu/hbase/Organic...

    This is called methyl propane. As you look at the drawing, you can see that there are three carbon atoms in straight line. This is why its last name is propane. The molecule has a methyl group bonded the center carbon atom. For these two reasons its name is methyl propane. I hope these two websites help you to understand how to draw the molecular formulas of these four compounds. As the number of carbon atoms increases, the number of isotopes increases.

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  • 8 months ago

    Your example is not well chosen. C3H8 does not have more than one structure. The only thing it can be is propane, which has a structure like this:

    https://www.instagram.com/p/BcsGwDvl6Sb/

    But when you get into higher numbers of carbon atoms, C4H10 for example, it might be n-butane or isobutane which have different structures.

    So in general, the formula alone is not enough to either name or draw a structure of the molecule.

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