How many σand π-bonds are there in the molecule of tetracyanoethylene? (a) 9 σand 9 π(b) 5 σand

How many σand π-bonds are there in the molecule of...

Key Concepts

Sigma Bonds

Sigma bonds are the primary covalent bonds formed by the direct, head-on overlap of atomic orbitals. They provide the skeletal framework for molecules and are present in both single bonds and as the first bond in multiple bonds. A clear understanding of sigma bonds is important because every covalent bond contains one sigma bond, regardless of whether additional pi bonds are present alongside it in double or triple bonds.

Pi Bonds

Pi bonds are formed by the lateral overlap of parallel orbitals after the formation of a sigma bond and are typically found in double and triple bonds. They play a key role in determining the electron density above and below the internuclear axis, which influences molecular reactivity, particularly in systems with conjugation or unsaturation. Analyzing pi bonds is important in understanding the overall bond order and the electronic properties of molecules.

Molecular Structure

Understanding the overall connectivity and arrangement of atoms in a molecule is crucial in predicting how atoms are bonded together. Knowing the structure provides insight into which atoms are directly bonded, the types of bonds present, and how substituents (like functional groups) are attached to the main framework of the molecule. This forms the basis for performing bond counts and for relating molecular geometry to reactivity and physical properties.

Bond Counting in Organic Molecules

Accurately counting the number of sigma and pi bonds in a molecule involves evaluating the types of bonds present based on its structure. This requires knowing how many connections exist between atoms, whether those bonds are single (one sigma), double (one sigma plus one pi), or triple (one sigma plus two pi). This counting process is fundamental in organic chemistry as it relates directly to the stability, reactivity, and physical characteristics of the molecule.

Transcript

00:02 Hi, in this problem, we are given a molecule that is tetra cyanothylene.

00:07 We have to tell the number of sigma bonds and pi bonds that are there in the molecule out of the given options a, b, c and d.

00:16 Now first of all, let's understand how many pi bonds and sigma bonds are presenting each type of covalent bond.

00:24 If a single covalent bond is present, this contains one sigma bond.

00:30 If a double covalent bond is present, it contains one sigma and one pi bond.

00:37 And in case of a triple covenant bond, whether it is carbon carbon or carbon nitrogen, it contains one sigma and two pi bonds.

00:47 Now, we will write the structure of this compound that can be shown as n triple bond bonded to carbon, this side again and triple bond c.

01:01 And there is a double bond beside the carbon which is further bonded to two c in groups, that is carbon, triple bond nitrogen.

01:11 Now we have all the bones shown in the given structure.

01:15 We will see the number of sigma and pi bonds.

01:18 Now carbon nitrogen bond here is a triple bond so it contains one sigma bond and two pi bonds.

01:27 In the same way, all the carbon nitrogen triple bond contains one sigma bond and two pi bonds each.

01:34 That is in this side, this scene group also has one sigma and two pi bonds.

01:41 Another scene group has one sigma and two pi bonds...

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