Group 7 - Displacement Reactions

• What is the name of the group in the periodic table that includes halogens?

  Group 7
• What do elements in the same group of the periodic table have in common?

  They have the same number of electrons in their outer shell
• What does the term 'halogen' mean?

  'Salt-producing' because they produce salts when reacting with metals
• What is a displacement reaction?

  A reaction where one substance takes the place of another
• What happens when chlorine reacts with potassium iodide?

  Chlorine displaces iodine from potassium iodide solution
• Write the balanced equation for the displacement reaction of chlorine with potassium iodide.

  Cl₂ (aq) + 2KI(aq) → 2KCl(aq) + I₂ (aq)
• Can iodine displace chlorine from sodium chloride solution?

  No, because iodine is less reactive than chlorine
• What happens to the size of atoms as you go down group 7?

  The atoms become larger
• Why does reactivity decrease as you go down group 7?

  Because the outer shell becomes further from the nucleus
• What is the effect of the distance of the outer shell from the nucleus on reactivity?

  The force of attraction decreases, making it harder to gain an outer electron
• What is the smallest part of an element that can exist?

  An atom
• What is an ion?

  An electrically charged particle formed when an atom gains or loses electrons
• What is the stable arrangement of electrons in ions?

  They have a complete outer shell
• What are the physical and chemical properties of Group 7 elements?

  Physical properties:

  • Diatomic molecules
  • Color varies from yellow-green (chlorine) to dark purple (iodine)

  
  

  Chemical properties:

  • Reactivity decreases down the group
  • Form salts with metals
• What is the result of adding chlorine to potassium bromide solution?

  Chlorine displaces bromine
• What is the result of adding bromine to potassium iodide solution?

  Bromine displaces iodine
• What is the result of adding iodine to potassium bromide solution?

  Iodine does not displace bromine
• What is the significance of the displacement reactions in Group 7 elements?

  They demonstrate the reactivity trends among halogens
• How do the properties of halogens change as you move down the group?

  They become less reactive and have higher boiling points
• What is the role of the nucleus in an atom?

  It contains protons and neutrons and has most of the mass of the atom
• What is the plural of nucleus?

  Nuclei
• What is the charge of halide ions?

  They have a single negative charge
• What are ionic compounds containing halide ions called?

  Halides
• What is the result of adding iodine to potassium chloride solution?

  Iodine does not displace chlorine
• What happens to the color of the reaction mixture when iodine is formed?

  The reaction mixture turns darker
• What is the chemical formula for potassium chloride?

  KCl
• What is the chemical formula for sodium bromide?

  NaBr
• What is the chemical formula for sodium iodide?


  NaI
• What is the chemical formula for potassium iodide?

  KI
• What is the significance of the periodic table?

  It organizes all known elements in groups and periods