Question

Match the following (a) \(\mathrm{F}_{2}\) (p) Metallic lusture (b) \(\mathrm{Cl}_{2}\) (q) Most electronegative (c) \(\mathrm{Br}_{2}\) (r) Highest bond energy (d) \(\mathrm{I}_{3}\) (s) Reddish liquid

Short answer

(a) \( \mathrm{F}_{2} \) — (q), (b) \( \mathrm{Cl}_{2} \) — (r), (c) \( \mathrm{Br}_{2} \) — (s), (d) \( \mathrm{I}_{3} \) — (p).

Step-by-step solution

Understand the Options

First, we need to recognize what the symbols represent. \( \mathrm{F}_{2} \), \( \mathrm{Cl}_{2} \), \( \mathrm{Br}_{2} \), and \( \mathrm{I}_{3} \) are diatomic or triatomic molecules of halogens. We need to match these to the given properties.

Assign Properties to Each Molecule

- \( \mathrm{F}_{2} \): Known for being the most electronegative element. Match with (q).- \( \mathrm{Cl}_{2} \): Known for having one of the highest bond energies among the halogens. Match with (r).- \( \mathrm{Br}_{2} \): Exists as a reddish-brown liquid at room temperature. Match with (s).- \( \mathrm{I}_{3} \): Though a polyatomic ion, it's associated with iodine, known for its metallic lustre. Match with (p).

Confirm the Matches

Ensure each molecule is correctly matched with its property:- (a) \( \mathrm{F}_{2} \) is (q) because it's the most electronegative.- (b) \( \mathrm{Cl}_{2} \) is (r) due to its high bond energy.- (c) \( \mathrm{Br}_{2} \) is (s) since it's a reddish liquid.- (d) \( \mathrm{I}_{3} \) is (p) because iodine has a metallic lustre.

Finalize the Matches

- (a) \( \mathrm{F}_{2} \) — (q) Most electronegative- (b) \( \mathrm{Cl}_{2} \) — (r) Highest bond energy- (c) \( \mathrm{Br}_{2} \) — (s) Reddish liquid- (d) \( \mathrm{I}_{3} \) — (p) Metallic lustre

Key concepts

Electronegativity

Electronegativity refers to the ability of an atom to attract electrons towards itself within a chemical bond. This concept is crucial for understanding chemical reactivity and bond formation. In the periodic table, electronegativity typically increases across a period—from left to right—and decreases down a group.

• Fluorine (_2) is the most electronegative element in the periodic table, which explains its strong attraction for electrons in chemical bonds.
• Electronegativity differences between atoms can predict the type of bonding: ionic, covalent, or polar covalent.
• A higher electronegativity indicates a stronger pull on electrons, resulting in polar bonds when paired with less electronegative elements.

Understanding electronegativity is key to predicting molecular structure and behavior, which further influences macroscopic properties like boiling point and solubility.

Diatomic Molecules

Diatomic molecules consist of two atoms bonded together. Essential for understanding chemistry, they are found among various elements, especially the halogens.

• Examples include _2 (fluorine), _2 (chlorine), and r_2 (bromine).
• The bond formed between the two atoms can significantly influence the molecule's stability and reactivity.
• Diatomic molecules can feature homonuclear (same element) or heteronuclear (different elements) compositions.

In the case of halogens, these diatomic molecules are commonly gases, with r_2 being an exception as a liquid. Their simple structure makes them an ideal starting point for studying chemical bonding principles.

Bond Energy

Bond energy is the measure of bond strength in a chemical bond. Specifically, it refers to the energy required to break one mole of bonds in gaseous molecules. Bond energy is a critical concept in understanding both chemical reactions and stability.

• _2 is known for having one of the highest bond energies among halogens, indicating strong Cl-Cl bonds.
• Higher bond energy implies a more stable molecule, which requires more energy to break apart.
• The concept of bond energy is used in calculating reaction enthalpies and understanding endothermic and exothermic processes.

Recognizing the bond energy helps in predicting reaction rates and determining how a molecule interacts with others, making it fundamental in both theoretical and practical chemistry.

Metallic Lustre

Metallic lustre describes the shiny appearance exhibited by metals and some non-metal substances. In the context of halogens, iodine and its compounds display this property.

• Iodine, though a non-metal, can appear metallic due to its crystal structure, which reflects light efficiently.
• This lustrous quality is not typical for other members of the halogen group, making iodine unique in this aspect.
• The observation of metallic lustre can aid in identifying substances and understanding their crystalline structures.

The metallic lustre of iodine is an intriguing exception among non-metals, highlighting diverse physical properties across the periodic table that contribute to the substance's characterization.