Lecture Notes: Group 7 and Group 0 Elements

Group 7 Elements: Halogens

• General Properties

  • Known as halogens
  • Dangerous and reactive
  • Exist as diatomic molecules (two atoms bonded)
  • Form covalent bonds with other non-metals (e.g., hydrogen fluoride, carbon tetrachloride)
  • Form ionic bonds with metals, creating halides (e.g., fluoride, chloride)

• Specific Halogens

  • Fluorine: Poisonous yellow gas, highly reactive
  • Chlorine: Poisonous green gas, less reactive than fluorine
  • Bromine: Reddy brown volatile liquid, poisonous
  • Iodine: Dark grey solid, forms poisonous purple vapours, also an antiseptic
  • Astatine & Tennessine: Not typically covered in the course

• Trends in Group 7

  • Melting and boiling points increase down the group
  • Reactivity decreases down the group
  • Decrease in reactivity is due to the increasing distance of the outer shell from the nucleus, weakening the attractive force for electrons

• Reactivity and Displacement Reactions

  • More reactive halogens can displace less reactive ones in compounds
  • Example: Chlorine can displace bromine in potassium bromide to form potassium chloride
  • Fluorine, chlorine, and bromine can displace iodine

Group 0 Elements: Noble Gases

• General Properties

  • Known as noble gases
  • Exist as colorless gases
  • Full outer shells, making them inert (non-reactive)
  • Exist as single atoms
  • Non-flammable

• Trends in Group 0

  • Boiling points increase as you go down the group

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End of Lecture