Skeletal Formula - Online Tutor, Practice Problems & Exam Prep

Skeletal formulas, also known as bond line or line formulas, are efficient representations of complex organic structures. In these formulas, carbon-carbon bonds are depicted as lines, with each corner representing a carbon atom. Hydrogen atoms attached to carbon are typically omitted, while other atoms like oxygen and nitrogen are shown. This method simplifies the drawing of organic compounds, allowing for a clearer understanding of molecular connectivity and functional groups, essential for studying organic chemistry.

Skeletal Formula Concept 1

In this video, we're going to take a look at skeletal formulas. Now, this is a representation, also known as a bond line or Line Formula, and it's the fastest way of drawing complex organic structures. As we go deeper and deeper into organic chemistry, we're going to move away from our structural formulas and condensed formulas because they take too long to draw. We're going to start incorporating more line, bond line, or skeletal formulas to draw more complex organic compounds. Now, here we have our structural formula which shows the connectivity between different atoms. We can package everything in more tightly, so it becomes CH₃ CH₂OH. This can be transformed into our skeletal formula. Now before we dissect it, let's go over a few guidelines here.

First, Carbon-Carbon Bonds are shown as lines, where every corner represents a carbon atom with enough hydrogen atoms. So, this here is a carbon, and this here is a carbon. And then if we continue, we land at the oxygen because there's an oxygen right here. Now, carbon and hydrogen atoms are not shown but other atoms such as oxygen, nitrogen, and sulfur are shown. So here, if we look, we have an oxygen right there. Then, we're going to say there's another exception to this, and that exception is hydrogen atoms attached to atoms other than carbon are shown. So if we look, we show this oxygen, and we show the hydrogen connected to it.

Now, if we take a look here, we're going to say we know that these two are carbons; carbon must make 4 bonds. So, this carbon here on the left, we see it making one bond to this carbon in the middle. It needs to make 4 bonds, so its 3 hydrogens aren't there, they're just invisible. The carbon in the middle, that carbon we see it making 2 bonds. Remember, carbon must make 4 bonds, so it has 2 hydrogens that are invisible. So, as we can see, without having to show all of this, I can just do this Skeletal Formula, and it represents the Condensed Formula, and it represents the Structural Formula. Again, Skeletal Formula is just a quick, faster way to draw these more complex organic compounds, and we're going to utilize them more and more as we delve deeper into organic chemistry.

Skeletal Formula Example 1

It says, determine the number of hydrogen atoms attached to each of the circled carbon atoms. Alright. So we know that every line represents a bond between two carbons. And remember, carbon must make 4 bonds. So the carbon on the left, we see it making one bond to this carbon in the middle. It needs 3 more bonds, which would mean that it has 3 hydrogens that we don’t see. Now, the carbon in the middle, let's go to this one. We see it making what? 1, 2, 3 bonds. Carbon must make 4 bonds, so it's one bond short, which means it has 1 hydrogen that's invisible. And then finally, the carbon on the right. We see this carbon here making 1, 2 bonds. Again, carbon must make how many bonds? 4. So it’s missing 2 more bonds, which means it has 2 hydrogens that are invisible. So here we’d have 3 hydrogens, 1 hydrogen, and then 2 hydrogens going from left to right. So this would be the number of H atoms on each one of these circled carbon atoms.

Draw a skeletal formula for the following molecule: CH₃CH(CH₃)CH₂CH₂OH.

• A.
• B.
• C.
• D.

Convert the following skeletal formula into condensed and structural formulas.

• A. Condensed: CH₃CH₂OHStructural:
• B. Condensed: CH₃CH₂CH₂(OH)CH₃Structural:
• C. Condensed: CH₃CH₂CH₂OHStructural:
• D. Condensed: CH₃CH(OH)CH₃Structural:

Here’s what students ask on this topic:

What is a skeletal formula in organic chemistry?

A skeletal formula, also known as a bond line or line formula, is a simplified representation of organic molecules. In this format, carbon-carbon bonds are depicted as lines, with each corner or endpoint representing a carbon atom. Hydrogen atoms attached to carbon are typically omitted, while other atoms like oxygen, nitrogen, and sulfur are shown. This method allows for a quicker and clearer depiction of complex organic structures, making it easier to understand molecular connectivity and functional groups. Skeletal formulas are particularly useful as you delve deeper into organic chemistry, where drawing detailed structural formulas can become cumbersome.

How do you draw a skeletal formula from a structural formula?

To draw a skeletal formula from a structural formula, follow these steps: 1) Identify all carbon atoms and represent them as corners or endpoints of lines. 2) Draw lines to represent carbon-carbon bonds. 3) Omit hydrogen atoms attached to carbon, but include hydrogen atoms attached to other atoms like oxygen or nitrogen. 4) Show all other atoms (e.g., O, N, S) explicitly. For example, the structural formula CH₃CH₂OH can be drawn as a skeletal formula with a line representing the C-C bond and an OH group at the end, indicating the presence of oxygen and its attached hydrogen.

Why are hydrogen atoms often omitted in skeletal formulas?

Hydrogen atoms attached to carbon are often omitted in skeletal formulas to simplify the drawing and make it less cluttered. Each carbon atom is understood to have enough hydrogen atoms to complete its four bonds. This convention allows chemists to focus on the more complex parts of the molecule, such as functional groups and the connectivity between carbon atoms. By omitting hydrogen atoms, skeletal formulas provide a clearer and more efficient way to represent large and complex organic molecules.

What are the advantages of using skeletal formulas in organic chemistry?

Skeletal formulas offer several advantages in organic chemistry: 1) They simplify the representation of complex molecules, making it easier to visualize and understand molecular structures. 2) They save time and space, as they omit hydrogen atoms attached to carbon and use lines to represent carbon-carbon bonds. 3) They highlight functional groups and molecular connectivity more clearly. 4) They are particularly useful for large organic molecules, where drawing detailed structural formulas would be cumbersome. Overall, skeletal formulas are an efficient and effective tool for studying and communicating organic chemistry concepts.

What is the difference between a skeletal formula and a structural formula?

A skeletal formula is a simplified representation of an organic molecule, where carbon-carbon bonds are shown as lines, and hydrogen atoms attached to carbon are omitted. Other atoms like oxygen, nitrogen, and sulfur are explicitly shown. In contrast, a structural formula provides a detailed depiction of the molecule, showing all atoms and bonds, including hydrogen atoms attached to carbon. While structural formulas offer a complete view of the molecule, skeletal formulas are more efficient for representing complex structures, making them useful for quick visualization and analysis in organic chemistry.