Group 2

• What is the atomic radius trend in the periodic table?

  Increases with more energy levels
• Why does the atomic radius increase down a group?

  Greater distance from nucleus and more energy levels
• How does shielding affect atomic radius?

  More shielding leads to a larger atomic radius
• What is the first ionization energy trend in the periodic table?

  Decreases as outer electron is further away
• Why is magnesium's ionization energy lower than expected?

  It has weaker lattice energy
• What is the reaction of Group 2 metals with cold water?

  • Produces metal hydroxide and hydrogen
  • Example: Mg(s) + H2O(l) → Mg(OH)2(aq) + H2(g)
  • Observations: effervescence, white precipitate
• What happens when Group 2 metals react with steam?

  • Produces metal oxide and hydrogen
  • Example: Mg(s) + H2O(g) → MgO(s) + H2(g)
  • Observations: white solid, burns with bright light
• What do metal oxides react with water to produce?

  Metal hydroxide
• What is the reaction of calcium oxide with water?

  CaO(s) + H2O(l) → Ca(OH)2(s)
• How does reactivity change in Group 2 metals?

  Increases down the group
• Why does reactivity increase down Group 2?

  More shielding makes outer electrons easier to lose
• What is the trend in melting points for Group 2 metals?

  Decreases down the group
• Why does the melting point decrease down Group 2?

  Due to decreased nuclear charge density
• What is the exception in the melting point trend of Group 2 metals?

  Magnesium is an exception
• How do you test for Group II ions and anions?

  • Barium ions form white precipitate with CO₃²⁻ or SO₄²⁻
  • Example: Ba²⁺(aq) + CO₃²⁻(aq) → BaCO3(s)
  • Observation: white precipitate
• What happens when metals react with acids?

  Produces ionic salt and hydrogen
• What is the reaction of magnesium with hydrochloric acid?

  Mg(s) + 2HCl → MgCl2(aq) + H2(g)
• What are the observations when magnesium reacts with hydrochloric acid?

  Bubbles of hydrogen gas and colourless solution
• What is the reaction of barium with water?

  Ba(s) + H2O(l) → Ba(OH)2(aq) + H2(g)
• What is the reaction of strontium with water?

  Sr(s) + H2O(l) → Sr(OH)2(aq) + H2(g)
• What is the reaction of barium oxide with water?

  BaO(s) + H2O(l) → Ba(OH)2(aq) + H2(g)
• What is the reaction of magnesium with steam?

  Mg(s) + H2O(g) → MgO(s) + H2(g)
• What is the reaction of magnesium with nitric acid?

  Mg(s) + 2HNO3 → Mg(NO2)2(aq) + H2(g)
• How do you test for carbonate ions?

  • Add HCl to the sample
  • Reaction: 2H+(aq) + CO₃²⁻(aq) → CO₂(g) + H₂O(l)
  • Observation: effervescence
• How do you test for sulfate ions?

  • Add HCl and then BaCl₂
  • HCl removes impurities like CO₃²⁻
  • Reaction: Ba²⁺(aq) + SO₄²⁻(aq) → BaSO₄(s)
  • Observation: white precipitate forms
• How do you test for magnesium ions?

  • Add solutions containing hydroxide ions
  • Formation of white precipitate indicates presence of Mg ions