Problem 141 - A Complete Resource Book in Chemistry for JEE Main

Question

Which of the following pairs is/are correctly matched here: (a) The strongest oxidizing agent - Iodine (b) The most reactive halogen - Fluorine (c) A halogen which is liquid at room temperature-Bromine (d) The most electronegative element-Fluorine

Step-by-Step Solution

Answer

Options (b), (c), and (d) are correctly matched.

Step 1: Understanding Oxidizing Agents

An oxidizing agent is a substance that gains electrons in a chemical reaction. Among halogens, the strength as an oxidizing agent decreases down the group. Therefore, in this case, iodine is not the strongest oxidizing agent. Instead, fluorine is the strongest oxidizing agent.

Step 2: Identifying the Most Reactive Halogen

The reactivity of halogens decreases down the group from fluorine to iodine. Fluorine is the most reactive halogen due to its high electronegativity and small atomic radius, which allows it to attract electrons easily.

Step 3: Determining the State of Halogens at Room Temperature

Halogens exist in different physical states at room temperature. Bromine is a halogen that is liquid at room temperature.

Step 4: Evaluating Electronegativity

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. Fluorine is the most electronegative element, which means it has the strongest tendency to attract electrons.

Key Concepts

Oxidizing Agents

Oxidizing agents play a crucial role in chemical reactions. They are substances that gain electrons and, in the process, oxidize another substance. Among halogens, which include fluorine, chlorine, bromine, iodine, and astatine, there is a trend in their ability to act as oxidizing agents.

• The strength of oxidizing agents decreases down the group in the periodic table.
• This means fluorine is the strongest oxidizing agent among the halogens, despite iodine being lower in the group.
• Fluorine's high electronegativity and small size make it extraordinarily effective at gaining electrons.

This trend is linked to their position in the periodic table and their atomic structures, making fluorine the most powerful oxidizing halogen.

Reactivity of Halogens

The reactivity of halogens is an important concept in chemistry that explains how easily these elements form compounds. Halogens are highly reactive nonmetals, and this reactivity decreases as we move down the group from fluorine to iodine.

• Fluorine is the most reactive halogen because of its small atomic size and high electronegativity, which allow it to attract electrons effectively and form compounds readily.
• As the atomic size increases from fluorine to iodine, the outer electrons are further from the nucleus, making it harder for the halogens to attract electrons.
• This makes iodine the least reactive halogen of the commonly discussed halogens.

The high reactivity of halogens is utilized in various industrial and chemical processes, emphasizing the need to handle these elements carefully.

Physical States of Halogens

Halogens display a fascinating range of physical states at room temperature, which classifies them as solids, liquids, and gases in their elemental forms. This variation is due to their atomic structure and intermolecular forces.

• Fluorine and chlorine are gases at room temperature.
• Bromine stands out as it is a liquid, showcasing the unique properties of halogens.
• Iodine and astatine are solids at room temperature.

Bromine's liquid state is particularly interesting, as it is one of the only nonmetals that is liquid at room temperature. This diverse range of states highlights the interesting and varied nature of halogens as a group.

Electronegativity

Electronegativity is a key concept in understanding how atoms interact in chemical bonds. It refers to the ability of an atom to attract electrons to itself when bonded to another atom. Halogens, and specifically fluorine, are known for their high electronegativity.

• Fluorine is the most electronegative element, giving it a strong pull on electrons in a bond.
• This high electronegativity is due to its small atomic radius and high effective nuclear charge.
• Chlorine, bromine, and iodine follow fluorine with decreasing electronegativity.

The concept of electronegativity is essential for predicting the behavior of molecules and their reactivity, making it a fundamental aspect of chemical education.