Interhalogen Compounds – Definition, Classification, Properties & Examples

In inorganic chemistry, interhalogen compounds are an important class of molecules composed of two or more different halogen atoms such as fluorine, chlorine, bromine, iodine or astatine. These compounds play a key role in understanding the reactivity and bonding trends of Group 17 elements and frequently appear in competitive exam questions for JEE, NEET and board exams. :contentReference[oaicite:0]{index=0}

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📌 What Are Interhalogen Compounds?

Interhalogen compounds are molecules that contain two or more different halogen atoms bonded together, with no atoms of any other element present. They form when elements in Group 17 react with one another. :contentReference[oaicite:1]{index=1}

In general, an interhalogen molecule is written as XY_n, where “X” and “Y” are two different halogen atoms. The value of n can be 1, 3, 5, or 7 — reflecting the odd valency of halogen atoms. :contentReference[oaicite:2]{index=2}

🧪 Why Do Interhalogen Compounds Form?

Halogens vary in electronegativity and atomic size. When a less electronegative, larger halogen atom (like iodine or bromine) reacts with a more electronegative, smaller halogen atom (like fluorine), they can form stable covalent bonds, resulting in interhalogen compounds. :contentReference[oaicite:3]{index=3}

📊 Classification of Interhalogen Compounds

Interhalogen compounds are classified based on the number of atoms in the molecule:

Diatomic Interhalogens (AX): e.g., ClF, IBr. :contentReference[oaicite:4]{index=4}
Tetratomic Interhalogens (AX₃): e.g., ClF₃, BrF₃. :contentReference[oaicite:5]{index=5}
Hexatomic Interhalogens (AX₅): e.g., BrF₅, IF₅. :contentReference[oaicite:6]{index=6}
Octatomic Interhalogens (AX₇): e.g., IF₇. :contentReference[oaicite:7]{index=7}

The symbol “X” refers to the halogen with relatively lower electronegativity (larger atom), while “Y” refers to the halogen that is more electronegative (smaller atom). :contentReference[oaicite:8]{index=8}

🔍 Examples of Interhalogen Compounds

ClF – Chlorine monofluoride
IBr – Iodine monobromide
ClF₃ – Chlorine trifluoride
BrF₅ – Bromine pentafluoride
IF₇ – Iodine heptafluoride

These examples show how interhalogen molecules vary in structure and composition, ranging from simple diatomic examples like IBr to more complex pentafluoride and heptafluoride species. :contentReference[oaicite:9]{index=9}

📈 General Properties of Interhalogen Compounds

Interhalogen compounds exhibit physical and chemical characteristics that are often intermediate between their constituent halogens. They are generally covalent and diamagnetic. Most interhalogens are more reactive than the original halogen molecules (except for fluorine in some cases). :contentReference[oaicite:10]{index=10}

Covalent Nature: All interhalogens form covalent bonds. :contentReference[oaicite:11]{index=11}
Reactivity: They tend to be more reactive than diatomic halogen molecules. :contentReference[oaicite:12]{index=12}
Volatility: Many are gases, liquids, or volatile solids at room temperature. :contentReference[oaicite:13]{index=13}
Hydrolysis: Interhalogens readily hydrolyse in water to give halogen acids and oxyacids. :contentReference[oaicite:14]{index=14}
Structure: Shapes such as bent, T-shaped, square pyramidal or pentagonal bipyramidal arise depending on the formula type. :contentReference[oaicite:15]{index=15}

🧪 Preparation of Interhalogen Compounds

Most interhalogen compounds are prepared by the direct combination of two halogen molecules under controlled conditions of temperature and pressure. For example:

Cl₂ + F₂ → 2ClF (formation of chlorine monofluoride)
I₂ + Cl₂ → 2ICl (formation of iodine monochloride)

Reactions between a lower interhalogen and a halogen can also yield higher interhalogen compounds. :contentReference[oaicite:16]{index=16}

📘 Importance & Applications

Interhalogen compounds are more than textbook definitions — they have real significance in both academic and industrial chemistry:

Useful in halogenation and fluorination reactions in organic synthesis.
Serve as oxidizing agents in various chemical processes.
Studied in advanced inorganic chemistry and spectroscopy.
Important for understanding periodic trends and bonding in Group 17 elements.

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📍 Conclusion

Interhalogen compounds are fascinating and vital molecules in inorganic chemistry. Understanding their formation, classification, properties, and behaviour helps strengthen your foundation for exams like JEE, NEET, and board chemistry. Once you grasp how halogens interact to form these compounds, many aspects of halogen chemistry become easier to predict and apply.

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Interhalogen compounds showing general formula, hybridization, and molecular shape

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