Problem 63 - A Complete Resource Book in Chemistry for JEE Main

Question

The bond between carbon atom (1) and carbon atom \((2)\) in compound \(\mathrm{N} \equiv \mathrm{C}-\mathrm{CH}=\mathrm{CH}_{2}\) involves the hybridization (a) \(\mathrm{sp}^{2}\) and \(\mathrm{sp}^{2}\) (b) \(\mathrm{sp}^{3}\) and sp (c) sp and sp² (d) sp and sp

Step-by-Step Solution

Answer

The hybridization is (c) sp and sp².

Step 1: Identify the Bond in Question

The exercise is asking about the hybridization of the bond between carbon atom (1) and carbon atom (2). In the compound \( \mathrm{N}\equiv \mathrm{C}-\mathrm{CH}=\mathrm{CH}_{2} \), carbon atom (1) is the one triple-bonded to nitrogen, and carbon atom (2) is the one single-bonded to it, on the left of the first double bond.

Step 2: Determine Hybridization of Each Carbon Atom

Carbon atom (1), which forms a triple bond with nitrogen, will have an sp hybridization because it needs two \(p\) orbitals for the formation of the triple bond. For carbon atom (2), which is connected by a single bond to carbon atom (1) and a double bond to carbon atom (3), sp² hybridization is needed to accommodate the double bond and the single bonds.

Step 3: Evaluate the Options

Now that we know the hybridization states: Carbon atom (1) is sp, and carbon atom (2) is sp². Find which option describes this scenario: Option (c) states "sp and sp²," which matches our determination.

Key Concepts

Hybridization of Carbon Atoms

Hybridization in chemistry refers to the concept of mixing atomic orbitals into new hybrid orbitals. These hybrid orbitals are designed to form chemical bonds extra effectively than their original state. Carbon atoms are especially fascinating in hybridization due to their ability to form a variety of bonds.

A single carbon atom can be hybridized in multiple ways, most commonly as sp³, sp², or sp. The type of hybridization depends largely on the number and type of bonds an atom will form.

• sp³ Hybridization: Occurs when one s and three p orbitals mix. It forms four equivalent sp³ hybrid orbitals, ideal for forming single bonds.
• sp² Hybridization: Involves one s and two p orbitals that combine. It results in three equivalent orbitals and commonly seen in double bonds.
• sp Hybridization: Takes place when one s and one p orbital merge, resulting in two hybrid orbitals. This is typical in triple bonds.

In the compound in the exercise, carbon atom (1) is sp hybridized to accommodate a triple bond with nitrogen, while carbon atom (2) is sp² hybridized, managing a double bond with the next carbon and a single bond with carbon atom (1). Understanding these hybridization types helps predict molecule shapes and their reactions.

Triple Bond in Chemistry

A triple bond is a type of chemical bond where two atoms, like carbon and nitrogen in the given compound, share three pairs of electrons. It's one of the strongest types of chemical bonds because of the large amount of energy required to break it.

Triple bonds are often found between lighter atoms like carbon, nitrogen, and oxygen. They are a crucial feature in unsaturated compounds which can show unique reactivity because of the potential energy stored within the bond.

• Structure: Triple bonds result in a linear arrangement of atoms since the participating atoms typically adopt an sp hybridization, aligning the orbitals linearly.
• Bonding Orbitals: The formation involves:
  • The overlap of one pair of s orbitals.
  • The presence of two pi bonds formed from the unhybridized p orbitals.

In the molecule described, the triple bond between the carbon and nitrogen atoms adds significant stability to the molecule. This type of bonding is unique due to its strength and the spatial arrangement, influencing both the physical and chemical properties of the molecule involved.

Carbon-Carbon Bond in Organic Compounds

Carbon-carbon bonds are the backbone of organic compounds. They form the skeleton of organic molecules and greatly influence the properties of the compound.

Carbon can form single, double, or triple bonds with other carbon atoms, leading to diverse structural possibilities within organic compounds.

• Single Bond (C-C): This involves two sp³ hybridized carbon atoms sharing a pair of electrons. Single bonds allow for rotational freedom, providing flexibility.
• Double Bond (C=C): A double bond consists of one sigma bond and one pi bond, involving sp² hybridization. This bond restricts rotation, creating planar geometry around the bond.
• Triple Bond: (C≡C) The strongest carbon-carbon bond, involving one sigma and two pi bonds formed from sp hybridization. This creates a linear alignment and rigid structure.

In the structure provided, carbon atom (2) sees two bonding scenarios: a single bond connecting it to carbon atom (1) and a double bond extending to carbon atom (3). This setup highlights the significance of carbon-carbon bonding combinations and how they dictate the overall geometry and reactivity of organic compounds.