Question

Determine the number of sigma bonds and pi bonds in each of the following molecules. H2C = CCl2 HOOC - COOH FHC = C = CHF

Answer 1

Concepts and reason

The concepts used to solve this problem are the concept of sigma bond (σ bond) and pi bonds (π bond). A sigma bond represents a covalent bond formed by head-on overlapping between atomic orbitals. A sigma bond represents the strongest covalent bond. A pi bond represents a covalent bond formed by the overlapping of atomic orbitals, which are in close contact through two overlap areas.

Fundamentals

To evaluate the total number of sigma and pi bonds, one must determine the total number of the single, double and triple bonds. A single bond comprises ${\rm{1}}$ sigma bond. A double bond comprises ${\rm{1}}$ sigma and ${\rm{1}}$ pi bond. A triple bond comprises ${\rm{1}}$ sigma and ${\rm{2}}$ pi bonds.

Part a.1

The chemical structure of the compound is as follows:

In this case, the above-mentioned structure comprises ${\rm{4}}$ single bonds and ${\rm{1}}$ double bond. Thus, the total number of sigma bonds is equivalent to ${\rm{5}}$ .

Part a.2

The chemical structure of the compound is as follows:

In this case, the above-mentioned structure comprises ${\rm{1}}$ double bond. Thus, the total number of pi bonds is equivalent to ${\rm{1}}$ .

Part b.1

The chemical structure of the compound is as follows:

In this case, the above-mentioned structure comprises ${\rm{5}}$ single bonds and ${\rm{2}}$ double bonds. Thus, the total number of sigma bonds is equivalent to ${\rm{7}}$ .

Part b.2

The chemical structure of the compound is as follows:

In this case, the above-mentioned structure comprises ${\rm{2}}$ double bonds. Thus, the total number of pi bonds is equivalent to ${\rm{2}}$ .

Part c.1

The chemical structure of the compound is as follows:

In this case, the above-mentioned structure comprises ${\rm{4}}$ single bonds and ${\rm{2}}$ double bonds. Thus, the total number of sigma bonds is equivalent to ${\rm{6}}$ .

Part c.2

The chemical structure of the compound is as follows:

In this case, the above-mentioned structure comprises ${\rm{2}}$ double bonds. Thus, the total number of pi bonds is equivalent to ${\rm{2}}$ .

Part d.1

The chemical structure of the compound is as follows:

In this case, the above-mentioned structure comprises ${\rm{6}}$ single bonds and ${\rm{2}}$ double bonds. Thus, the total number of sigma bonds is equivalent to ${\rm{8}}$ .

Part d.2

The chemical structure of the compound is as follows:

In this case, the above-mentioned structure comprises ${\rm{2}}$ double bonds. Thus, the total number of pi bonds is equivalent to ${\rm{2}}$ .

Ans: Part a.1

The total number of sigma bonds in the given structure is ${\rm{5}}$ .

Part a.2

The total number of pi bonds in the given structure is ${\rm{1}}$ .

Part b.1

The total number of sigma bonds in the given structure is ${\rm{7}}$ .

Part b.2

The total number of pi bonds in the given structure is ${\rm{2}}$ .

Part c.1

The total number of sigma bonds in the given structure is ${\rm{6}}$ .

Part c.2

The total number of pi bonds in the given structure is ${\rm{2}}$ .

Part d.1

The total number of sigma bonds in the given structure is ${\rm{8}}$ .

Part d.2

The total number of pi bonds in the given structure is ${\rm{2}}$ .