Group 2

• What are the elements in Group 2 called?

  Alkaline Earth Metals
• What are the chemical trends in Group 2 elements?

  • Two electrons in outermost shell
  • Form +2 ions by donating electrons
  • Reactivity increases down the group
  • Ionization energies decrease down the group
• What is the first ionization energy?

  Energy needed to remove the first outer electron
• How does the ionization energy change down Group 2?

  It decreases going down the group
• Why do Group 2 elements become more reactive down the group?

  It becomes easier to lose outer electrons
• What effect does increased shielding have on ionization energy?

  It decreases the attraction to outer electrons
• What happens to the atomic radius of Group 2 elements down the group?

  It increases going down the group
• How does the melting point trend in Group 2 elements?

  It decreases going down the group
• What causes the decrease in melting point down Group 2?

  Outer electrons are further from the nucleus
• What is the trend in density for Group 2 elements?

  Density drops then increases down the group
• What is the solubility trend for Group 2 hydroxides?

  • Solubility increases going down the group
  • More alkaline solutions formed
  • Mg(OH) is sparingly soluble
  • Ba(OH) is soluble
• What happens to the solubility of Group 2 sulfates down the group?

  It decreases going down the group
• How can you test for sulfate ions using barium sulfate?

  Form a white precipitate with barium ions
• What are the general reactions of Group 2 elements with water?

  • React with water to form hydroxides
  • Produce hydrogen gas
  • Be does not react with water
• What is the general equation for Group 2 metals reacting with oxygen?

  2M (s) + O$_2$ (g) → 2MO (s)
• What is the reaction of magnesium with water?

  Mg (s) + 2H$_2$O (l) → Mg(OH)$_2$ (aq) + H$_2$ (g)
• How does the reactivity of radium compare to barium?

  Radium is more reactive than barium
• What is the expected pH of radium hydroxide compared to calcium hydroxide?

  Radium hydroxide has a higher pH
• What is the formula for radium oxide?

  RaO
• What is the general formula for Group 2 hydroxides?

  X(OH)$_2$
• What happens when radium hydroxide reacts with dilute sulfuric acid?

  A white precipitate of radium sulfate forms
• What are the observations for Group 2 reactions with oxygen and water?

  • Mg: Burns easily, bright white light
  • Ca: Difficult to ignite, red flame
  • Sr: Difficult to ignite, red flame
  • Ba: Difficult to ignite, green flame
• What are the general trends in reactivity for Group 2 elements?

  • Reactivity increases down the group
  • Ionization energy decreases down the group
  • Metals react more vigorously with acids
• What is the general equation for the reaction of group 2 metals with oxygen?

  2M (s) + O (g) → 2MO (s)
• Which group 2 metals form a peroxide?

  Strontium and Barium
• What is the general equation for the reaction of metals with water?

  M (s) + 2H₂O (l) → M(OH)₂ (s) + H₂ (g)
• Which group 2 metal does not react with water?

  Beryllium
• What are the reactions of group 2 metals with water and oxygen?

  • Group 2 metals react with oxygen to form oxides.
  • They react with water to form hydroxides and hydrogen gas.
  • Beryllium does not react with water.
• What is the reaction of magnesium with oxygen?

  2Mg (s) + O₂ (g) → 2MgO (s)
• What is the reaction of magnesium with water?

  Mg (s) + 2H₂O (l) → Mg(OH)₂ (aq) + H₂ (g)
• What is the reaction of calcium with oxygen?

  2Ca (s) + O₂ (g) → 2CaO (s)
• What is the reaction of calcium with water?

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

  2Sr (s) + O₂ (g) → 2SrO (s)
• What is the reaction of strontium with water?

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

  2Ba (s) + O₂ (g) → 2BaO (s)
• What is the reaction of barium with water?

  Ba (s) + 2H₂O (l) → Ba(OH)₂ (aq) + H₂ (g)
• How does magnesium react with cold water compared to steam?

  Slowly with cold water, vigorously with steam
• What is the pH of the solution formed when magnesium reacts with water?

  pH 9−10
• What is the reaction of magnesium with steam?

  Mg (s) + H₂O (g) → MgO (s) + H₂ (g)
• What happens when group 2 metals react with dilute acids?

  • They form colorless solutions of metal salts.
  • Hydrogen gas is produced as a by-product.
  • Example: Metal chlorides from hydrochloric acid.