Halogens - Group 7A ✏ Chemistry In a Nutshell

Rucete ✏ Chemistry In a Nutshell

Group 7A Halogens Summary

General Characteristics

• Elements: Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), Astatine (At)
• Electron Configuration: ns²np⁵
• Nonmetals, Diatomic (X₂) in Nature
• Highly Reactive: Do not exist as free elements in nature.
• High Ionization Energy & Strong Electron Affinity: Readily gain electrons to form X⁻ (halide ions).

Element Breakdown

Fluorine (F)

• Most reactive of all halogens.
• Reacts with water to produce oxygen.

Chlorine (Cl), Bromine (Br), Iodine (I)

• Form halide compounds (ionic or covalent).
• Exist as diatomic molecules Cl₂, Br₂, I₂.

Astatine (At)

• Radioactive and extremely rare.

Key Chemical Reactions & Properties

1. Halogens form Ionic & Covalent Compounds:

   • Combine with metals to form halide salts (e.g., NaCl, KBr).
   • Can also form covalent molecular compounds.

2. Reactivity with Hydrogen:

• Form hydrogen halides (HX), such as HCl, HBr, HI.
• Hydrogen halides dissolve in water to form halogen acids (hydrohalic acids):
• Strong Acids: HCl, HBr, HI.
• Weak Acid: HF (Hydrofluoric Acid).

Key Trends & Properties

1. Reactivity Decreases Down the Group:
   F > Cl > Br > I > At

2. Acidity of Hydrogen Halides (HX):

   • HF is a weak acid due to strong H-F bonding.
   • HCl, HBr, HI are strong acids.

3. Melting & Boiling Points Increase Down the Group:

• Fluorine & Chlorine → Gases
• Bromine → Liquid
• Iodine & Astatine → Solids

In a Nutshell

• All are diatomic nonmetals.
• F is the most reactive, At is radioactive.
• HCl, HBr, HI are strong acids, HF is weak.