Organic Chemistry — Bonding and Structure: Interpret Chemical Structure Line Drawing
Question
How many carbons are in the following drawing? How many hydrogens?
Show/Hide Answer
5 carbons; 10 hydrogens
Refer to Section 7.2: Drawing Chemical Structures (1).
Strategy Map
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Check out the strategy map.
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| Strategy Map Steps |
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1. Identify the carbons in the line drawing for the molecule.
Show/Hide HintIn a line structure, carbon atoms are found at the end of each line as well as at each corner. |
2. Add hydrogen atoms to the carbons until each carbon has 4 bonds.
Show/Hide HintThis will satisfy the octet rule. |
| 3. Count the carbon atoms and the hydrogen atoms in the molecule. |
Solution
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The full Lewis Structure shows that this molecule has 5 carbon atoms and 10 hydrogen atoms.
Guided Solution
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The guided solution below will give you the reasoning for each step to get your answer, with reminders and hints.
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| Guided Solution Ideas |
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This question is a theory problem that requires you to identify all implied carbons and hydrogens in a line structure.
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What do the lines represent? Where are the implied carbons and hydrogens?
Show/Hide Don’t Forget!Recall that in a line structure, carbon atoms are found at the end of each line as well as at each corner. Hydrogen atoms surround the carbons to satisfy the octet rule. |
Draw the structure of the molecule showing all carbon and hydrogen atoms. Remember to fulfill the octet rule.
Show/Hide Don’t Forget!Recall your steps for drawing Lewis Structures. Refer to Section 4.4: Lewis Symbols and Structures (2). |
| Complete Solution |
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| In a line structure, carbons are at either end of each line as well as in every corner. A double line shows the double bond.
Start by writing in the carbon atoms and their connectivity based on the line diagram. Show/Hide Structure!
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Then, add hydrogen atoms to each C atom until each C has 4 bonds.
Show/Hide Structure!
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| Count the carbon and hydrogen atoms shown in the structure.
Answer: In this molecule, there are 5 carbon atoms and 10 hydrogen atoms. |
Check Your Work
Summary of what we would expect based on the related chemistry theory
Show/Hide Watch Out!
Counting valence electrons, there are 4 for each C and 1 for each H, making a total of 30 valence electrons. The Lewis Structure shows 30 valence electrons and satisfies the octet rule.
Does your answer make chemical sense?
Show/Hide Answer
The full structure represents the Lewis Structure for this molecule. There are 5 carbon atoms, which matches the line structure given in the question, and 10 hydrogen atoms, which satisfies the octet rule for each carbon.
There are many ways to draw molecules. A line structure gives us the ability to quickly create carbon-hydrogen structures. By convention, we know that each line represents the carbon-to-carbon bond and that all hydrogen atoms are “hidden.”
Refer to Section 4.4: Lewis Symbols and Structures (2).
PASS Attribution
- LibreTexts PASS Chemistry Book CHEM 1500 (3).
- Question 7.2 from LibreTexts PASS Chemistry Book CHEM 1500 (4) is used under a CC BY-NC-SA 4.0 license.
- Question 7.2 is question 7.2.2 from LibreTexts CHEM 1500: Chemical Bonding and Organic Chemistry (1) is used under a CC BY-SA 4.0 license.
- Question 7.2.2 is question 1.12.2 from LibreTexts Organic Chemistry (Morsch et al.) (5), which is under a CC BY-SA 4.0 license.
Media Attributions
- All figures are by Ashlynn Jensen, from LibreTexts PASS Chemistry Book CHEM 1500 (4) by Blackstock et al., and are used/updated under a CC BY-NC 4.0 license.
References
1. Farmer, S.; Kennepohl, D.; Cunningham, K.; Soderburg, T.; Reusch, W. 7.2: Drawing Chemical Structures. In CHEM 1500: Chemical Bonding and Organic Chemistry; LibreTexts, 2022. https://chem.libretexts.org/Courses/Thompson_Rivers_University/CHEM_1500%3A_Chemical_Bonding_and_Organic_Chemistry/07%3A_Organic_Chemistry_I_-_Bonding_and_Structure/7.02%3A_Drawing_Chemical_Structures.
2. Elles, L. S. 4.4 Lewis Symbol and Structures. In CHEM 130 and 135: General Chemistry I and II (Sharpe Elles); LibreTexts, 2023. https://chem.libretexts.org/Courses/University_of_Kansas/CHEM_130%3A_General_Chemistry_I_(Sharpe_Elles)/04%3A_Chemical_Bonding_and_Molecular_Geometry/4.04%3A_Lewis_Symbols_and_Structures#:~:text=We%20use%20Lewis%20symbols%20to,period%20of%20the%20periodic%20table.
3. Blackstock, L.; Brewer, S.; Jensen, A. PASS Chemistry Book CHEM 1500; LibreTexts, 2023. https://chem.libretexts.org/Courses/Thompson_Rivers_University/PASS_Chemistry_Book_CHEM_1500.
4. Blackstock, L.; Brewer, S.; Jensen, A. 7.2: Question 7.2 PASS – Interpret Chemical Structure Line Drawing. In PASS Chemistry Book CHEM 1500; LibreTexts, 2023. https://chem.libretexts.org/Courses/Thompson_Rivers_University/PASS_Chemistry_Book_CHEM_1500/07%3A_Organic_Chemistry_I_-_Bonding_and_Structure/7.02%3A_Question_7.2_PASS_-_interpret_chemical_structure_line_drawing.
5. Farmer, S.; Kennepohl, D.; Cunningham, K.; Soderburg, T.; Reusch, W. 1.12: Drawing Chemical Structures . In Organic Chemistry (Morsch et al.); LibreTexts, 2023. https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Organic_Chemistry_(Morsch_et_al.)/01%3A_Structure_and_Bonding/1.12%3A_Drawing_Chemical_Structures.
