Problem 89 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following is the strongest oxidizing agent? (a) \(\mathrm{F}_{2}\) (b) \(\mathrm{Cl}_{2}\) (c) \(\mathrm{Br}_{2}\) (d) \(\mathrm{I}_{2}\)

Step-by-Step Solution

Answer

The strongest oxidizing agent is \text{F}_2 (Fluorine).

Step 1: Understanding Oxidizing Agents

Oxidizing agents are substances that gain electrons during a chemical reaction. The stronger the oxidizing agent, the more readily it accepts electrons. In the context of halogens, the oxidizing strength generally decreases as we move down the group in the periodic table.

Step 2: Identify the Halogens

The elements listed in the options,  ext{F}_2,  ext{Cl}_2,  ext{Br}_2, and  ext{I}_2, are all halogens. They are ordered in the periodic table as follows: Fluorine ( ext{F}_2), Chlorine ( ext{Cl}_2), Bromine ( ext{Br}_2), and Iodine ( ext{I}_2).

Step 3: Analyze the Periodic Trend

For halogens, the ability to act as an oxidizing agent decreases as the atomic number increases, meaning it becomes less powerful as you move down the group. Thus, fluorine is expected to be the strongest oxidizing agent, followed by chlorine, bromine, and iodine.

Step 4: Determine the Strongest Oxidizing Agent

Based on the periodic trends and the given options,  ext{F}_2 (Fluorine) should be the strongest oxidizing agent among the given choices, because it is at the top of the group and has the highest tendency to gain electrons.

Key Concepts

Halogens

Halogens are a group of elements found in Group 17 of the periodic table. This group includes fluorine ( F_2 ), chlorine ( Cl_2 ), bromine ( Br_2 ), and iodine ( I_2 ). These elements are known for their high reactivity, especially with metals. The reason behind this reactivity is their electron configuration.
Halogens all have seven electrons in their outer shell, just one shy of the full octet. This makes them very eager to gain that extra electron in order to achieve a stable electron configuration. This tendency to gain an electron explains why they are very good oxidizing agents. Let's break down each halogen:

• Fluorine ( F_2 ): The most reactive and the strongest oxidizing agent. It has the highest electronegativity, meaning it strongly attracts electrons.
• Chlorine ( Cl_2 ): Less electronegative than fluorine but still a strong oxidizer. It's used in many disinfection processes.
• Bromine ( Br_2 ): Moderately reactive; it is often used in flame retardants.
• Iodine ( I_2 ): The least reactive among these, with a critical role in nutrition, like the production of thyroid hormones.

Understanding the behavior of halogens is crucial for predicting their role in various chemical reactions.

Periodic Table Trends

The periodic table is a powerful tool for understanding chemical behavior and predicting element properties. It arranges elements in increasing atomic number and groups similar elements together. Within the periodic table, there are specific trends that are important when evaluating elements like halogens.
One key trend is electronegativity, which is a measure of how strongly an atom attracts electrons. In general:

• Electronegativity increases across a period from left to right.
• Electronegativity decreases down a group.

This means that in the group of halogens, fluorine is the most electronegative, making it the strongest oxidizing agent. Trends, like atomic size, also play a role. As you move down the group:

• Atomic size increases.
• Electronegativity decreases.

Both trends contribute to the reactivity of the elements. Smaller atoms with higher electronegativities, like fluorine, can more easily attract additional electrons.

Chemical Reactions

Chemical reactions involve the breaking and forming of bonds between atoms, which results in the transformation of substances. These reactions can be grouped into different types, but one common theme in all reactions is the transfer or sharing of electrons between atoms.
For halogens, these reactions often involve gaining electrons from other elements, which classifies them as oxidizing agents. In an oxidation-reduction (redox) reaction, an oxidizing agent gains electrons from another substance. This allows the oxidizing agent to become reduced, while the other substance becomes oxidized.
Oxidizing agents are crucial in a variety of chemical processes.

• Disinfection: Chlorine and its compounds are used to disinfect water, making it safe to drink.
• Combustion: Oxygen, although not a halogen, is another common oxidizing agent in combustion processes.
• Synthesis: Halogens are used in the synthesis of organic compounds, altering the structure and properties of the compounds.

Understanding the role of oxidizing agents and how they interact in chemical reactions helps in predicting the outcome of these processes and their practical applications.