Skeletal Formula - Online Tutor, Practice Problems & Exam Prep

Skeletal formulas, also known as bond line or line formulas, are streamlined representations of complex organic structures, crucial for efficiently conveying molecular connectivity in organic chemistry. These formulas depict carbon-carbon bonds as lines with each corner signifying a carbon atom, implicitly surrounded by the appropriate number of hydrogen atoms to satisfy carbon's tetravalency. Unlike carbon and hydrogen, heteroatoms like oxygen, nitrogen, and sulfur are explicitly shown, as are hydrogens attached to them. This method of drawing organic compounds simplifies the depiction of molecules, omitting the need to draw every single bond and atom, thereby making it easier to visualize and understand larger and more complex molecules. As proficiency in organic chemistry grows, the use of skeletal formulas becomes increasingly important for both clarity and speed in communication.

Skeletal Formula

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 lined 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 chapter three, Chapter 20. 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 year is a carbon, and this here's 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 H Adams attached to other atoms 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 four bonds. So this carbon here on the left, we see making one bond to this carbon in the middle, it needs to make four bonds. So it's 3 hydrogens are there, they're just invisible.

The carbon in the middle, that carbon, we see it making two bonds. Remember, carbon must make four bonds. So it has two 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

Here it says determine the number of hydrogen atoms attached to each of the circled carbon atoms. All right, so we know that every line represents a connection between 2 carbons. And remember, carbon must make four bonds. So the carbon on the left, we see it making one bond to this carbon. In the middle. It needs three more bonds, which would mean that it has three hydrogens that we don't see.

Now, the carbon in the middle. Let's go to this one. We see it making what? 123 bonds. Carbon must make four bonds. So it's one bond short, which means it has one 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 two more bonds, which means it has two hydrogens that are invisible.

So here we'd have 3 hydrogens, 1 hydrogens, and then two 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:

How do you read a skeletal formula?

Reading a skeletal formula, which is a shorthand representation of a molecule in organic chemistry, involves understanding that lines represent bonds between atoms and the ends of lines or intersections represent carbon atoms. Here's a step-by-step guide:

1. Carbon Atoms: Each end of a line and each intersection of lines indicates a carbon atom. These are often not labeled in skeletal formulas.
2. Hydrogen Atoms: Hydrogen atoms bonded to carbons are not usually shown. Each carbon atom is assumed to be bonded to enough hydrogen atoms to give the carbon a total of four bonds.
3. Other Atoms: Atoms other than carbon and hydrogen, known as heteroatoms (like oxygen, nitrogen, sulfur, etc.), are explicitly drawn and labeled with their elemental symbols.
4. Multiple Bonds: Double or triple bonds between carbon atoms are shown with two or three lines, respectively.
5. Branches and Rings: Branches in the carbon chain are shown as lines branching off the main "skeleton." Carbon atoms that are part of a ring structure are depicted by a polygon (triangle, square, pentagon, etc.), with each corner representing a carbon atom.
6. Functional Groups: Specific arrangements of atoms that impart characteristic chemical properties to a molecule are drawn explicitly and are important for understanding the molecule's reactivity and interactions.

This is the skeletal formula for which molecule?

To provide an answer to the question about the skeletal formula of a molecule, I would need to see the actual image or description of the skeletal formula you're referring to. A skeletal formula is a way of representing the structure of an organic compound using lines for bonds and letters for atoms, with the understanding that each intersection (vertex) and line terminus represents a carbon atom with sufficient hydrogens to satisfy the carbon's valence. Without the specific image or description, I cannot determine which molecule is represented. If you can provide the skeletal formula or describe it in detail, I would be able to help identify the molecule for you.

What is a skeletal representation of a molecular formula?

A skeletal representation of a molecular formula, also known as a skeletal structure or skeletal formula, is a simplified way of drawing organic compounds where carbon atoms are not shown explicitly and hydrogen atoms attached to carbons are also omitted. In these diagrams, carbon atoms are represented by the ends of lines (bonds) and by the vertices where lines meet. Each vertex or line end corresponds to a carbon atom.

The lines themselves represent the bonds between atoms; a single line indicates a single bond, a double line a double bond, and so on. Atoms other than carbon and hydrogen, known as heteroatoms (like oxygen, nitrogen, sulfur, etc.), are usually represented by their elemental symbols. Hydrogen atoms that are bonded to heteroatoms are normally shown, as their presence or absence can be significant for the molecule's properties.

This method of representation makes it easier to quickly draw and interpret complex organic molecules, focusing on the connectivity of the carbon skeleton and the functional groups present without cluttering the diagram with the numerous hydrogen atoms that would be present in a full structural formula.

How do you write a molecular formula from a skeletal structure?

To write a molecular formula from a skeletal structure, you need to identify all the atoms and the number of each type present in the molecule. Here's a step-by-step process:

1. Identify Carbon Atoms: Each vertex (corner) and the end of each line in the skeletal structure represents a carbon atom unless otherwise specified.
2. Add Hydrogen Atoms: Carbon atoms typically form four bonds. Count the bonds that each carbon atom forms in the skeletal structure and add enough hydrogen atoms to make four bonds. If a carbon is bonded to three other atoms, it will have one hydrogen. If it's bonded to two other atoms, it will have two hydrogens, and so on.
3. Identify Other Atoms: Look for atoms that aren't carbon or hydrogen. These will often be labeled with their chemical symbols (like O for oxygen, N for nitrogen, etc.).
4. Count Atoms: Tally up the number of each type of atom present in the structure.
5. Write the Formula: Write the molecular formula by listing the symbols for the elements starting with carbon (C), then hydrogen (H), followed by the other elements in alphabetical order. Next to each symbol, write the number of atoms of that element present in the molecule as a subscript.

Remember, the skeletal structure is a simplified representation, so it