Key Points
Key Points: Group 17 Elements - The Halogen Family
General electronic configuration: ns² np⁵
| Element | Symbol | Configuration |
|---|---|---|
| Fluorine | F | [He] 2s² 2p⁵ |
| Chlorine | Cl | [Ne] 3s² 3p⁵ |
| Bromine | Br | [Ar] 3d¹⁰ 4s² 4p⁵ |
| Iodine | I | [Kr] 4d¹⁰ 5s² 5p⁵ |
| Astatine | At | [Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵ |
Trends in Different Properties:
| Property | Trend |
|---|---|
| Enthalpy of Dissociation | Cl₂ > Br₂ > F₂ > I₂ |
| Dipole Moment | HF > HCl > HBr > HI |
| Ionic Character | HI < HBr < HCl < HF |
| Bond Length | HF < HCl < HBr < HI |
| Bond Strength | HI < HBr < HCl < HF |
| Thermal Stability | HI < HBr < HCl < HF |
| Reducing Power | HF < HCl < HBr < HI |
| Acid Strength | HF < HCl < HBr < HI |
Key Points: Anomalous Behaviour of Fluorine
Reasons
- Small atomic size
- Very high electronegativity
- Absence of d-orbitals
- Low F–F bond dissociation energy
| Property | Fluorine |
|---|---|
| Oxidation state | Only −1 (does not show + states) |
| Hydride | HF is liquid (others are gases) |
| Nature | Form more ionic compounds |
| Oxyacids | Forms only one oxyacid (HOF) |
Key Points: Interhalogen Compounds
Types of Interhalogen Compounds:
| Type | Examples |
|---|---|
| XX′ | ClF, BrF, ICl, IBr |
| XX′₃ | ClF₃, BrF₃, IF₃ |
| XX′₅ | ClF₅, BrF₅, IF₅ |
| XX′₇ | IF₇ |
Methods of Preparation:
| Method | Reactions |
|---|---|
| Direct combination | Cl₂ + F₂ → 2ClF Br₂ + 3F₂ → 2BrF₃ I₂ + 3Cl₂ → 2ICl₃ |
| Halogen + interhalogen | Br₂ + BrF₃ → 3BrF Br₂ + ClF₃ → 2BrF₃ + BrCl |
| Special (ICl) | I₂ + KClO₃ → ICl + KIO₃ |
Key Points: Oxoacids of Halogens
| Oxidation state of X | Generic name | Oxoacids of fluorine | Oxoacids of chlorine | Oxoacids of bromine | Oxoacids of iodine |
|---|---|---|---|---|---|
| +1 | Hypohalous acid (HXO) | HOF | HOCl | HOBr | HOI |
| +3 | Halous acid (HXO₂) | – | HOClO | – | – |
| +5 | Halic acid (HXO₃) | – | HOClO₂ | HOBrO₂ | HOIO₂ |
| +7 | Perhalic acid (HXO₄) | – | HOClO₃ | HOBrO₃ | HOIO₃ |
Important Questions [22]
- Draw Structure of Chlorine Pentafluoride
- Iodine Exists as
- Arrange the following in the increasing order of the property mentioned: MF, MCl, MBr, MI (ionic character)
- Write Any ‘Four Points’ of Difference Between Fluorine and Other Halogens.
- Describe Anomalous Behaviour of Fluorine with the Other Elements of Group 17 Wilh Reference to
- What is the Action of Chlorine (Cl) on the Following: Potassium Bromide Solution
- Arrange the following oxyacids of chlorine - HClO, HClO2, HClO3, and HClO4 with respect to increasing order of oxidizing power.
- Write Any Two Uses of Chlorine
- What is the Action of Chlorine on : Cs2
- Answer the following. What is the action of chlorine on Excess NH3.
- Which of the Following Compounds of Chlorine is Used as Refrigerant?
- Write the chemical reaction,when chlorine reacts with dry slaked lime.
- Arrange the following oxyacids of chlorine - HClO, HClO2, HClO3, and HClO4 with respect to increasing order of thermal stability.
- What happens when thin copper leaves are thrown in jar containing chlorine?
- What is the Action of Chlorine (Cl) on the Following: Cold and Dilute Caustic Soda
- What is the Action of Chlorine (Cl) on the Following: Hot and Concentrated Caustic Soda
- Write ‘Four’ Uses of Hydrochloric Acid.
- Draw the Structure of If7. Write Its Geometry and the Type of Hybridization.
- Draw Structure of Chlorine Trifluoride
- Explain the Structure of Trifluoride
- Write Chemical Formula of the Following Oxoacids of Chlorine
- Arrange the Following Oxyacids of Chlorine in Decreasing Order of Their Thermal Stability. Give Reason. Hoclo, Hocl, Hclo4, Hoclo2
