group 7

• What does the word halogen mean?

  Salt former
• How do halogens typically react with metals?

  They form fluoride, chloride, bromide, and iodide salts
• What are the physical states and colors of the gaseous halogens at room temperature?

  • Fluorine: pale yellow gas
  • Chlorine: greenish gas
  • Bromine: red-brown liquid
  • Iodine: black solid
• What is a characteristic smell of halogens?

  Swimming-bath smell
• Why are some properties of fluorine untypical?

  F-F bond is unexpectedly weak
• What causes the repulsion in fluorine atoms?

  Non-bonding electrons are too close together
• What trend is observed in the size of halogen atoms down the group?

  • Atoms get bigger going down the group
  • Each element has one extra filled main level of electrons
• What is the atomic number of fluorine?

  9
• What is the atomic number of chlorine?

  17
• What is the atomic number of bromine?

  35
• What is the atomic number of iodine?

  53
• What is the electron arrangement of fluorine?

  [He] 2s² 2p⁵
• What is the electron arrangement of chlorine?

  [Ne] 3s² 3p⁵
• What is the electron arrangement of bromine?

  [Ar] 3d¹⁰ 4s² 4p⁵
• What is the electron arrangement of iodine?

  [Kr] 4d¹⁰ 5s² 5p⁵
• What is electronegativity and what factors affect it?

  • Measure of an atom's ability to attract electrons
  • Depends on:
  • Nuclear charge
  • Distance to bonding electrons
  • Shielding effect of inner electrons
• How does electronegativity change down Group 7?

  It decreases going down the group
• What trend is observed in melting and boiling points of halogens?

  • Melting and boiling points increase down the group
  • Due to stronger van der Waals forces
• Why is chlorine more volatile than iodine?

  Chlorine is a gas, iodine is a solid
• What is the trend in oxidizing ability of halogens?

  It increases going up the group
• What do halogens typically become when they gain electrons?

  Negative ions with a charge of -1
• What is the role of halogens in redox reactions?

  They act as oxidizing agents
• What happens in a displacement reaction involving halogens?

  A more reactive halogen displaces a less reactive one
• What is the ionic equation for the displacement reaction of chlorine and bromide ions?

  Cl₂ + 2NaBr → Br₂ + 2NaCl
• What color change occurs in the displacement reaction of chlorine and bromide ions?

  Colorless to red-brown
• Why can't fluorine be investigated in aqueous solution?

  It reacts with water
• What is the method for extracting bromine from seawater?

  • Chlorine oxidizes bromide ions
  • Produces bromine from seawater
• How is iodine extracted from kelp?

  • Kelp is burned to obtain iodine
  • Residue treated with manganese dioxide and sulfuric acid
• What happens to halide ions in reactions with concentrated sulfuric acid?

  They can act as reducing agents
• What is the reaction of sodium chloride with concentrated sulfuric acid?

  Produces sodium hydrogensulfate and hydrogen chloride
• Why is the reaction of sodium chloride with sulfuric acid not a redox reaction?

  No oxidation state has changed
• What is produced when sodium bromide reacts with concentrated sulfuric acid?

  Hydrogen bromide and bromine fumes
• What is the significance of the sodium ions in the displacement reaction?

  They are spectator ions
• What is the trend in reducing ability of halide ions?

  • Reducing ability increases down the group
  • Larger ions lose electrons more easily
• How does the size of halide ions affect their reducing ability?

  Larger ions lose electrons more easily
• What is produced when sodium fluoride reacts with concentrated sulfuric acid?

  Hydrogen fluoride gas
• Why is hydrogen fluoride considered dangerous?

  It can etch glass
• What is the general trend in the reactions of sodium halides with concentrated sulfuric acid?

  • Different products reflect reducing powers
  • Stronger reducing agents produce more products
• What is the reaction between sodium chloride and sulfuric acid?

  NaCl(s) + H₂SO₄(l) → NaHSO₄(s) + HCl(g)
• Why is the reaction between sodium chloride and sulfuric acid not a redox reaction?

  No oxidation state has changed