Group 7

• What type of elements are group 7 elements?

  Highly reactive non-metals
• Why do group 7 elements need to gain an electron?

  To form a 1- ion and achieve stability
• What happens to the atomic radius of group 7 elements down the group?

  It increases
• Why does reactivity decrease down group 7 elements?

  Increased atomic radius weakens nucleus attraction
• What is the trend of first ionisation energy in group 7 elements?

  It decreases down the group
• What causes the boiling point of group 7 elements to increase down the group?

  Stronger van der Waals forces with higher Ar
• What state is fluorine at room temperature?

  Gas
• What state is iodine at room temperature?

  Solid
• How do halogens act as oxidising agents?

  They accept electrons and are reduced
• What happens to oxidising power down group 7 elements?

  It decreases
• What does the relative oxidising strength of halogens indicate?

  A halogen displaces any halide beneath it
• What are halide ions?

  Negative ions of halogens
• How do halide ions act as reducing agents?

  They donate electrons and are oxidised
• What trend occurs in reducing power down group 7 elements?

  It increases
• What is the significance of the reducing power in redox reactions?

  Longer reactions with powerful halides
• What is used to test for halide ions?

  Acidified silver nitrate
• What do the different coloured precipitates indicate in halide tests?

  Different halide ions present
• What precipitate forms with chloride ions and silver nitrate?

  White precipitate (AgCl)
• What precipitate forms with bromide ions and silver nitrate?

  Cream precipitate (AgBr)
• What precipitate forms with iodide ions and silver nitrate?

  Yellow precipitate (AgI)
• What happens to the precipitate of chloride ions when dilute ammonia is added?

  Precipitate dissolves
• What happens to the precipitate of bromide ions when dilute ammonia is added?

  No change occurs
• What happens to the precipitate of iodide ions when dilute ammonia is added?

  No change occurs
• What happens to the precipitate of chloride ions when concentrated ammonia is added?

  Precipitate dissolves
• What happens to the precipitate of bromide ions when concentrated ammonia is added?

  Precipitate dissolves
• What happens to the precipitate of iodide ions when concentrated ammonia is added?

  No change occurs
• What ions does chlorine produce when it reacts with cold water?

  Chlorate(I) ions and chloride ions
• What type of reaction occurs when chlorine reacts with cold water?

  Disproportionation reaction
• What happens to the oxidation state of chlorine in the disproportionation reaction?

  It goes from 0 to +1 and -1
• What does chlorine produce in the presence of UV light when reacting with water?

  Oxygen and hydrochloric acid
• What is a risk associated with using chlorine in water treatment?

  Chlorine can be toxic
• What is produced when chlorine is mixed with cold, aqueous sodium hydroxide?

  Sodium hypochlorite
• What is the purpose of acidifying silver nitrate in tests for halides?

  To remove impurities that could precipitate
• What precipitate forms when sulfate ions react with BaCl₂?

  White precipitate
• How can hydroxide ions be identified?

  Using red litmus that turns blue
• What happens when an acid is added to carbonate ions?

  Effervescence occurs and CO₂ is released
• How can carbon dioxide be confirmed after reacting with carbonate ions?

  By bubbling through limewater which turns cloudy
• What method is used to identify group 2 cations?

  Flame tests
• What color does calcium produce in a flame test?

  Brick red
• What color does strontium produce in a flame test?

  Red