Group 7 Elements

• What are the Group 7 elements commonly known as?

  Halogens
• What is the trend observed in the reactivity of halogens as you move down Group 7?


  They become less reactive
• What type of elements are the halogens?


  Non-metals
• What is the physical state and color of fluorine?


  It is a very reactive, poisonous, pale yellow gas
• Describe the physical state and color of chlorine.


  It is a fairly reactive, poisonous, dense green gas
• What is the state and color of bromine at room temperature?


  Bromine is a dense, poisonous, red-brown volatile liquid
• What is the physical state and appearance of iodine?


  Iodine can be a dark grey crystalline solid or a purple vapor
• How do halogens exist in nature?


  As molecules which are pairs of atoms
• What are the trends observed as you go down Group 7 for halogens?


  1. Become less reactive
  2. Have higher melting and boiling points
  3. Have higher relative atomic masses
• Why do all Group 7 elements react in similar ways?


  They all have seven electrons in their outer shell
• How do halogens form molecular compounds?


  • Halogen atoms share electrons via covalent bonding
  • Achieve a full outer shell
  • Examples: HCl, PCl₃, HF, CCl₄
• What happens when halogens react with metals?


  • They form 1- ions called halides (F⁻, Cl⁻, Br⁻, I⁻)
  • Example compounds: NaCl, FeBr₃
  • The compounds have ionic structures
• What is a displacement reaction in the context of halogens?


  A more reactive halogen can displace a less reactive one from its salt
• Give an example of a displacement reaction involving halogens.


  Chlorine can displace bromine and iodine from their salts
• What is the balanced symbol equation for the displacement reaction between bromine and sodium iodide?


  Br₂ + 2NaI → 2NaBr + I₂
• Why do Group 7 elements get less reactive as you go down the group?


  It becomes harder to gain an extra electron as the outer shell is further from the nucleus
• What is the significance of displacement reactions in chemistry?


  • Important for understanding reactivity trends
  • Demonstrates the behavior of halogens
  • Useful in predicting chemical reactions
• What do group 7 elements need for a full outer shell?


  1 electron
• How can group 7 elements react to achieve a full outer shell?


  • Sharing electrons
  • Gaining an electron
• What type of bond do halogens form when they share electrons with non-metals?


  Covalent bonds
• What is the representation of a single covalent bond between two fluorine atoms?


  F - F
• What do halogens form when they gain an electron during a reaction with metals?


  • Ionic compounds
  • Form 1- ions
• What happens in a displacement reaction involving halogens?


  More reactive halogens displace less reactive halogens
• What is the chemical equation for the displacement reaction of chlorine and potassium bromide?


  Cl₂ + 2KBr → Br₂ + 2KCl
• What is the chemical equation for the reaction of chlorine with potassium iodide?

  Cl₂(aq) + 2KI(aq) → 2KCl(aq) + I₂(aq)
• What happens to the size of atoms as you go down group 7?


  • Atoms become larger
  • Outer shell becomes further from the nucleus
  • Forces of attraction decrease
• How does the distance of the outer shell from the nucleus affect the reactivity of halogens?


  It makes gaining an outer electron less easy
• What happens to the reactivity of halogens as you go down group 7?


  The halogen becomes less reactive