Question

Which of the following is a false statement? (1) The name benzene was given to it by Mitcherlich. (2) The correct structure for benzene was first proposed by Kekule. (3) The orbital overlap between carbon atoms in benzene is sp-sp. (4) Benzene molecule is plane hexagonal.

Short answer

Statement 3 is false (The orbital overlap between carbon atoms in benzene is sp^2-sp^2).

Step-by-step solution

Understand the question

Identify which of the given statements about benzene is false.

Analyze Statement 1

The name benzene was given to it by Mitcherlich. This statement is true as the benzene compound was indeed described and named by Eilhard Mitcherlich.

Analyze Statement 2

The correct structure for benzene was first proposed by Kekule. This statement is also true because August Kekule proposed the hexagonal structure of benzene with alternating double and single bonds.

Analyze Statement 3

The orbital overlap between carbon atoms in benzene is sp-sp. This is false because the correct orbital overlap in benzene is sp^2-sp^2, due to each carbon in benzene being sp^2 hybridized.

Analyze Statement 4

Benzene molecule is plane hexagonal. This statement is true as benzene is a planar molecule with a regular hexagonal structure.

Conclusion

Given all the analysis, the false statement is identified.

Key concepts

benzene naming

Benzene was named by Eilhard Mitcherlich in the 19th century when he distilled it from benzoic acid. The name 'benzene' is derived from the word 'gum benzoin,' an aromatic resin known since ancient times. Benzene is a fundamental compound in organic chemistry. Its simple ring structure and stability make it a base for many other chemicals. Understanding how benzene was named helps in recognizing its historical significance and role in the development of organic chemistry. Benzene's discovery and naming marked a crucial point in chemistry, leading to more in-depth study of aromatic compounds.

Modern chemistry uses benzene as a reference for many other aromatic compounds, influencing nomenclature, structural study, and chemical synthesis.

orbital overlap

Orbital overlap is crucial in understanding benzene's stability and bonding. Each carbon atom in benzene undergoes sp² hybridization, resulting in three sp² hybrid orbitals and one unhybridized p orbital. The sp² orbitals form \(\text{sp}^2 - \text{sp}^2\) sigma bonds with neighboring carbon atoms and hydrogen atoms. This forms a planar hexagonal structure with 120-degree bond angles. The unhybridized p orbitals, one on each carbon, overlap sideways. This creates a delocalized \(\text{π}\) electron cloud above and below the plane of the benzene ring.

The delocalization of electrons in the \(\text{π}\) system explains benzene's stability and its resistance to addition reactions, which would disrupt this electron cloud. This 'ring' of electrons is often referred to as aromatic stabilization, a key feature that gives benzene its unique properties.

molecular geometry

Benzene's molecular geometry is planar hexagonal. Each carbon atom in the benzene ring forms three sigma bonds: one with a hydrogen atom and two with adjacent carbon atoms. This arrangement maintains the flat, hexagonal structure of benzene. The planar structure is a result of sp² hybridization, resulting in 120-degree angles between bonds. The equal length of all carbon-carbon bonds is due to the resonance structure of benzene.

• The planar geometry ensures delocalization of \(\text{π}\) electrons.
• The molecular symmetry gives benzene its unique chemical properties.

The uniformity in bond lengths and angles due to resonance provides additional stability to the structure.

Understanding this molecular geometry is essential in grasping the chemical behavior of benzene.

Kekule structure

August Kekule first proposed the structure of benzene as a ring with alternating double and single bonds in 1865. This important discovery helped explain benzene's unique properties and reactivity. The Kekule structure depicted benzene as a flippable hexagon with three double bonds, suggesting a rapid interconversion between two structures. This concept introduces the idea of resonance in benzene. The actual structure of benzene is a hybrid of these Kekule structures. The modern understanding of benzene involves delocalized \(\text{π}\) electrons throughout the ring, rather than fixed double bonds.

Key points to remember:

• Kekule's model was crucial in progressing the understanding of aromatic compounds.
• The structure is now observed as a resonance hybrid with equal bond lengths.

The concept of resonance adds to the explanation of benzene's stability and alternating bond nature, showcasing the dynamic nature of chemical bonding theories over time.