Understanding Halogen Oxidizing Nature

The question asks us to arrange the halogens in the increasing order of their oxidizing nature. Oxidizing nature refers to the ability of a substance to gain electrons, causing another substance to be oxidized while the oxidizing agent itself gets reduced.

Halogens are elements in Group 17 of the periodic table. They are known for being strong oxidizing agents because they readily accept one electron to achieve a stable noble gas configuration.

Trend of Oxidizing Nature in Halogens

The halogens are arranged in Group 17 from top to bottom as follows:

• Fluorine (F)
• Chlorine (Cl)
• Bromine (Br)
• Iodine (I)

The oxidizing nature of halogens generally decreases as we move down the group from Fluorine to Iodine. This trend is primarily due to factors like:

• Atomic Size: The atomic size increases down the group. The incoming electron needs to be accommodated in a shell farther from the nucleus.
• Nuclear Charge Effect: Although nuclear charge increases, the increased shielding effect from inner electrons reduces the effective nuclear attraction felt by the valence electrons and the incoming electron.
• Electron Affinity: While electron affinity shows some irregularities (Chlorine has a slightly higher electron affinity than Fluorine), the overall ability to attract and hold an electron weakens significantly from Chlorine downwards to Iodine.
• Bond Dissociation Enthalpy and Hydration Enthalpy: For halogens reacting in aqueous solutions, other factors like the energy required to break the X-X bond (\(\text{X}_2 \rightarrow 2\text{X}\)) and the energy released when the halide ion is hydrated (\(\text{X}^-_{(g)} \rightarrow \text{X}^-_{(aq)}\)) also play a role in determining their oxidizing strength. However, the general trend driven by electron affinity and atomic size is that oxidizing power decreases down the group.

Therefore, the decreasing order of oxidizing nature among halogens is:

\(\text{F} > \text{Cl} > \text{Br} > \text{I}\)

Arranging in Increasing Order

Since the decreasing order of oxidizing nature is \(\text{F} > \text{Cl} > \text{Br} > \text{I}\), the increasing order will be the reverse:

\(\text{I} < \text{Br} < \text{Cl} < \text{F}\)

This means Iodine has the weakest oxidizing nature, followed by Bromine, then Chlorine, and Fluorine has the strongest oxidizing nature among the halogens.

Comparing with Options

Let's look at the given options and see which one represents the correct increasing order:

The arrangement I, Br, Cl, F correctly represents the increasing order of the oxidizing nature of halogens.

Revision Table: Halogen Properties

Additional Information: Displacement Reactions

The difference in oxidizing nature of halogens can be observed in displacement reactions. A stronger oxidizing halogen can oxidize (and displace) a halide ion of a weaker oxidizing halogen from its solution.

• \(\text{Cl}_2\) is a stronger oxidizing agent than \(\text{Br}_2\) and \(\text{I}_2\). So, \(\text{Cl}_2\) can displace \(\text{Br}^-\) and \(\text{I}^-\) ions.

  Example: \(\text{Cl}_{2(aq)} + 2\text{KBr}_{(aq)} \rightarrow 2\text{KCl}_{(aq)} + \text{Br}_{2(aq)}\)

• \(\text{Br}_2\) is stronger than \(\text{I}_2\). So, \(\text{Br}_2\) can displace \(\text{I}^-\) ions.

  Example: \(\text{Br}_{2(aq)} + 2\text{KI}_{(aq)} \rightarrow 2\text{KBr}_{(aq)} + \text{I}_{2(aq)}\)

• \(\text{I}_2\) is the weakest oxidizing agent among these three and cannot displace \(\text{Cl}^-\) or \(\text{Br}^-\) ions.
• Fluorine (\(\text{F}_2\)) is the strongest oxidizing agent and can displace \(\text{Cl}^-\), \(\text{Br}^-\), and \(\text{I}^-\) ions. However, \(\text{F}_2\) reacts violently with water, producing oxygen or ozone, which complicates its reactions in aqueous solutions compared to the other halogens.

Understanding the trend in oxidizing nature helps predict the outcome of such reactions.