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HALOGEN, Feature: strong oxidizing property: X₂ + 2e → 2X‾ And descending…
HALOGEN
Chemical properties
Reacting with water
Fluorine oxidizes water easily at ambient temperature, causing combustion
H₂O + 2F₂ → 4HF + O₂
Cl₂, Br₂, I₂ occur oxidation-reduction process
X₂ + H₂O ⇌ HX + HXO
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Reacting with alkali solution
(X is Chlorine, Bromine or Iodine)
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Reacting with metals
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Cl₂, Br₂, I₂: oxidizes most metals. Chlorine reacts with metals more stronger than bromine, with iodine needs to be heated
2Fe + 3Cl₂ → 2FeCl₃
Fe + Br₂ →FeBr₂ (and one part FeBr₃ less durable)
Fe + I₂ → FeI₂
Applications
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Chlorine is used in the preparation of R-X derivatives, pesticides, PVC, HCl, Javel, lime chloride production
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Used as flame retardants, electronic components, materials, product casings and plastics
Bromine is used in pharmaceuticals, dyes, printing inks, film coatings and make swimming pool water disinfectantly
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A few characteristics
From fluorine to iodine, atomic radius increases gradually, electronegativity decreases gradually
Fluorine has only an oxidation number of -1 in every compound, other halogens have an oxidation number of -1,+1,+3,+5,+7
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Include: fluorine(Z=9), chlorine(Z=17), bromine(Z=35), iodine(Z=53) and astatine(Z=85)
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Physical properties
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Most of them smell bad, unpleasant and very toxic
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Melting temperature, boiling temperature increases gradually
Modulations
General principle of free halogen modulation 2X‾ →X₂ + 2e with powerful oxidants,...
Fluorine has the strongest oxidizing property, so it can only be prepared by using current to oxidize the F‾ ion in molten fluoride.
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