Group 7

• What is the physical state and color of fluorine (F2)?

  Very pale yellow gas
• What is the physical state and color of chlorine (Cl2)?

  Greenish, reactive gas
• What is the physical state and color of iodine (I2)?

  Shiny grey solid
• What is the trend in melting and boiling points of halogens down the group?

  • Melting and boiling points increase down the group
  • Larger molecules have more electrons
  • Larger van der Waals forces require more energy to break
• What is the trend in electronegativity of halogens down the group?

  • Electronegativity decreases down the group
  • Atomic radii increase due to more shells
  • Nucleus less able to attract bonding electrons
• What is the definition of electronegativity?

  Attraction of an atom for electrons in a bond
• What happens in displacement reactions of halide ions by halogens?

  • Strong oxidizing halogen displaces weaker halogen
  • Oxidizing strength decreases down the group
  • Chlorine displaces bromide and iodide ions
• What color solution indicates the presence of chlorine in a reaction?

  Very pale green solution
• What color solution indicates the presence of bromine in a reaction?

  Yellow solution
• What color solution indicates the presence of iodine in a reaction?

  Brown solution
• What is the reaction of chlorine with potassium bromide?

  Chlorine displaces bromide ions
• What is the reaction of chlorine with potassium iodide?

  Chlorine displaces iodide ions
• What is the test for halide ions using silver nitrate?

  • Acidify with nitric acid
  • Add silver nitrate dropwise
  • Observe precipitate color:
  • Fluorides: no precipitate
  • Chlorides: white precipitate
  • Bromides: cream precipitate
  • Iodides: pale yellow precipitate
• What precipitate do chlorides produce with silver nitrate?

  White precipitate
• What precipitate do bromides produce with silver nitrate?

  Cream precipitate
• What precipitate do iodides produce with silver nitrate?

  Pale yellow precipitate
• How can silver halide precipitates be differentiated?

  • Silver chloride dissolves in dilute ammonia
  • Silver bromide dissolves in concentrated ammonia
  • Silver iodide does not react with ammonia
• What happens when halides react with concentrated sulfuric acid?

  • F- and Cl-: acid-base reactions only
  • Br-: reduces sulfur from +6 to +4
  • I-: reduces sulfur from +6 to -2
• What is the observation when fluoride reacts with concentrated sulfuric acid?

  White steamy fumes of HF
• What is the observation when chloride reacts with concentrated sulfuric acid?

  White steamy fumes of HCl
• What is the observation when bromide reacts with concentrated sulfuric acid?

  White steamy fumes of HBr and orange fumes of bromine
• What is the observation when iodide reacts with concentrated sulfuric acid?

  White steamy fumes of HI and black solid iodine
• What is disproportionation in the context of chlorine reactions?

  • Chlorine simultaneously oxidizes and reduces
  • Cl2(g) + H2O(l) -> HClO(aq) + HCl(aq)
• What happens when chlorine reacts with water in sunlight?

  Produces oxygen gas and chloride ions
• What is the reaction of chlorine with cold dilute NaOH?

  • Cl2(aq) + 2NaOH(aq) -> NaCl(aq) + NaClO(aq) + H2O(l)
  • Used as bleach and disinfectant
• How are chlorates and sulfates named in IUPAC convention?

  • Include oxidation number in Roman numerals
  • Examples:
  • NaClO: sodium chlorate(I)
  • K2SO4: potassium sulfate(VI)
• What is the oxidation state of sulfur in K2SO4?

  +6
• What is the oxidation state of sulfur in K2SO3?

  +4
• What is the oxidation state of chlorine in NaClO3?

  +5
• What is the oxidation state of chlorine in NaClO?

  +1
• What is the product of the reaction between Cl₂ and Br⁻?

  2Cl⁻ and Br₂
• What is the product of the reaction between Cl₂ and I⁻?

  2Cl⁻ and I₂
• What is the product of the reaction between Br₂ and I⁻?

  2Br⁻ and I₂
• What is the purpose of adding nitric acid in the halide ion test?

  • To make the solution acidic
  • To prevent carbonate precipitate formation
  • To ensure accurate halide identification
• What precipitate do fluorides produce in the halide test?

  No precipitate
• What precipitate do chlorides produce in the halide test?

  White precipitate
• What is the reaction for chloride ions with silver nitrate?

  Ag⁺ + Cl⁻ → AgCl(s)
• What precipitate do bromides produce in the halide test?

  Cream precipitate
• What is the reaction for bromide ions with silver nitrate?

  Ag⁺ + Br⁻ → AgBr(s)
• What precipitate do iodides produce in the halide test?

  Pale yellow precipitate