Question

The different forms of a molecule having different arrangement of atoms arc called (1) Tautomers (2) Isomers (3) Canonical forms (4) \(\mathrm{Al} 1\)

Short answer

Isomers

Step-by-step solution

- Understanding the Question

Identify what the question is asking about: different forms of a molecule with different arrangements of atoms.

- Define Key Terms

Define the terms given in the options. 1. Tautomers: Isomers that can interconvert by chemical reactions.2. Isomers: Compounds with the same molecular formula but different structural formulas.3. Canonical forms: Different structures representing the same species in resonance.4. Al 1: This doesn't relate to molecular structures.

- Analyze the Options

Evaluate each option based on the definitions. Tautomers refer to a specific type of isomers. Canonical forms are different resonance structures, not different spatial arrangements of atoms. 'Al 1' does not apply here.

- Choose the Correct Answer

Based on the definitions and analysis, identify the correct choice: Isomers.

Key concepts

isomers

Isomers are fascinating molecules! They have the same molecular formula but share different structural arrangements.
This means that although they have identical amounts of each type of atom, these atoms are connected in varied ways.
Let's break this down a bit:

• **Structural Isomers**: Differ in how their atoms are connected. Think of them as creative reconfigurations.
• **Stereoisomers**: Same bond structure, different 3D arrangement. These include geometric isomers (cis-trans) and optical isomers (enantiomers).

Here's a simple analogy: Imagine isomers as identical building blocks arranged into different shaped structures. One might be a car, another a boat. Same blocks, different outcomes! Understanding isomers enhances our grasp of chemical diversity and behavior. Cool, right?

tautomers

Tautomers are a special type of isomer that can switch between forms by chemical reaction.
They usually involve a proton moving, and a shift in bonds within a molecule.
For example:

• **Keto-enol tautomerism**: Common in carbonyl compounds, where a keto form (C=O) converts to an enol form (C=C-OH).
• **Imine-enamine tautomerism**: Where an imine (C=NH) shifts to an enamine (C=C-NH2).

The transformation is dynamic and can create balance within a solution. Tautomers often showcase how molecules can exist in equilibrium, dancing between distinct forms. It’s a beautiful chemical ballet!

canonical forms

Canonical forms, also known as contributing structures, are different ways to represent a molecule in resonance.
Resonance helps describe delocalized electrons within molecules where one structure isn't enough.
Keep in mind:

• Canonical forms are NOT real structures. They are hypothetical representations.
• The actual molecule is a blend or hybrid of these forms.

Consider benzene, C6H6, a classic example. It doesn't flip between structures but rather exists as a resonance hybrid of its canonical forms. Canonical forms are useful for understanding the distribution of electron density and predicting molecule behavior.

resonance structures

Resonance structures are similar but distinct from canonical forms.
They are actual, plausible configurations of a molecule where the electrons are distributed differently.
Important points include:

• Real bonds and atoms don’t move between resonance structures.
• The actual molecule is a resonance hybrid, more stable than any single resonance form.

For instance, the nitrate ion (NO3-) has three resonance structures that distribute the negative charge evenly across the molecule, leading to a more stable overall structure. Resonance is crucial for understanding the true nature of molecules with delocalized electrons. It fine-tunes our chemical perception.