MediumChemistryHigh School (11–12)Organic Chemistry: Some Basic Principles and Techniques › Classification, IUPAC Nomenclature and IsomerismNumericalpython
Write pent-1-en-3-yne as CH2=CH-C C-CH3, with a double bond between the first two carbons and a…
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Write pent-1-en-3-yne as CH2=CH-C#C-CH3, with a double bond between the first two carbons and a triple bond between the third and fourth. Find how many of its carbon atoms are , and . Then find the total number of sigma bonds and pi bonds.
Need a reminder? The key ideaShow
Carbon forms four bonds. Four atoms around it: , tetrahedral, 109.5 degrees. Three atoms around it: , planar, 120 degrees. Two atoms around it: , linear, 180 degrees. Every bond holds one sigma bond. A double bond adds one pi bond, and a triple bond adds two. In a bond-line drawing, every corner and every end is a carbon atom, and each carbon has four bonds in all.
The worked solution
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The five carbons. has three atoms around it, so . has three: . The two carbons of the triple bond each have two atoms around them: . The carbon has four: .
Step 2. Sigma bonds. The four C-C links give 4. The hydrogen atoms are 2 + 1 + 3 = 6, which give 6 C-H bonds. Total: 10.
Step 3. Pi bonds. The double bond gives 1 and the triple bond gives 2. Total: 3.
Answer: one , two and two carbons; 10 sigma bonds and 3 pi bonds.
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