Group 7

• The halogens are in the p block because their outer electrons are in the p
• What type of molecules do the halogens exist as?

  Diatomic
• Trends in halogen properties as you move down the group

  1️⃣ Atomic radius increases

  2️⃣ Boiling point increases

  3️⃣ Electronegativity decreases

  4️⃣ First ionisation energy decreases
• The atomic radius of halogens increases down the group due to more shells
• The ionic radius of a halide ion is larger than its corresponding atom due to weaker attraction with the nucleus.
• What happens to the boiling point of halogens as you go down the group?

  Increases
• The increase in boiling point down the group is due to stronger van der Waals forces
• What happens to electronegativity as you move down the group?

  Decreases
• The first ionisation energy of halogens decreases down the group due to increased shielding
• Match the halogen with its state at room temperature:

  Chlorine ↔️ Green gas

  Bromine ↔️ Red-brown liquid

  Iodine ↔️ Black solid
• Which type of solvent are halogens more soluble in?

  Non-polar
• The solubility of halogens in water decreases as the molecule becomes larger.
• Steps to perform a displacement reaction of halogens

  1️⃣ Add a solution of each halogen to a solution of each potassium halide

  2️⃣ Note any colour changes

  3️⃣ Decide whether a reaction has occurred
• When chlorine reacts with potassium bromide, the solution turns orange
• What is the full equation for the reaction between chlorine and potassium bromide?

  Cl₂ + 2KBr → 2KCl + Br₂
• The oxidising ability of halogens increases down the group.

  False
• What is disproportionation in redox reactions?

  Same element oxidised and reduced
• Match the observation with the substance:

  Pale green solution ↔️ Cl₂

  Blue litmus turns red ↔️ HCl

  Litmus paper is bleached ↔️ HClO
• Chloric(I) acid decomposes in sunlight to form hydrochloric acid and oxygen
• What is a benefit of using chlorine in water treatment?

  Kills bacteria
• Chlorine is toxic in large quantities, posing a risk in water treatment.
• What is a common example of a halide salt?

  Sodium chloride
• In the test for halide ions, dilute nitric acid is added to remove carbonates
• Match the halide ion with its precipitate color after adding silver nitrate:

  Cl⁻ ↔️ White precipitate

  Br⁻ ↔️ Cream precipitate

  I⁻ ↔️ Yellow precipitate
• Fluoride ions form a precipitate with silver nitrate because silver fluoride is insoluble in water.

  False
• What is the color and formula of the precipitate formed when silver nitrate reacts with chloride ions?

  White, AgCl
• Fluoride ions form a precipitate with silver nitrate because silver fluoride is insoluble in water.

  False
• What observation is made when silver nitrate solution is added to sodium fluoride solution?

  No visible change
• The ionic equation for the reaction of silver nitrate with sodium chloride is Ag⁺(aq) + Cl⁻(aq) → AgCl(s), forming a white precipitate.
• What is the color of the precipitate formed when silver nitrate reacts with bromide ions?

  Cream
• What is the color of the precipitate formed when silver nitrate reacts with iodide ions?

  Yellow
• Match the silver halide precipitate with its behavior in ammonia solution:

  Silver chloride ↔️ Dissolves in dilute ammonia

  Silver bromide ↔️ Dissolves in concentrated ammonia

  Silver iodide ↔️ Remains insoluble
• What is the formula of the complex ion formed when silver chloride dissolves in ammonia?

  [Ag(NH₃)₂]⁺
• What is the definition of a reducing agent?

  An electron donor
• Halides act as reducing agents by donating electrons to form halogens.
• Halide ions react differently with concentrated sulfuric acid due to their varying reducing strengths.
• Match the sulfur compound with its oxidation number:

  H₂SO₄ ↔️ +6

  SO₂ ↔️ +4

  S ↔️ 0

  H₂S ↔️ -2
• What are the two types of reactions that occur when a solid halide salt reacts with concentrated sulfuric acid?

  Acid-base and redox
• What are the oxidation and reduction products when sodium chloride reacts with concentrated sulfuric acid?

  HCl and H₂SO₄
• What are the oxidation and reduction products when sodium bromide reacts with concentrated sulfuric acid?

  Br₂ and SO₂