21.2.2 The Alkaline Earth Metals

Question 1

The Alkaline Earth Metals

Answer 1

• Group 2(IIA) elements are called alkaline earth metals.
• Alkaline earth metals form 2+ cations and react with water and oxygen.
• Four important alkaline earth metals are beryllium, magnesium, calcium, and barium.

Question 2

note

Answer 2

• Group 2(IIA) elements are called alkaline earth metals.
• Like alkali metals, alkaline earth metals react with water and oxygen.
• However, alkaline earth metals are harder, denser, and have higher boiling points than alkali metals.
• Alkaline earth metals form 2+ cations.
• Beryllium is found in the mineral beryl. Emerald and
  aquamarine are two forms of beryl, with different impurities resulting in the colors.
• Magnesium forms several different minerals, including
  dolomite (CaCO 3 ·MgCO 3 ), magnesite (MgCO 3 ), epsomite (MgSO 4 ·7H 2 O), and brucite (Mg(OH) 2 ).
• Magnesium hydroxide (Mg(OH 2 )) is milk of magnesia, an antacid.
• Magnesium is isolated from seawater through the Dow process.
• Mg 2+ (aq) + 2OH – (aq) -> Mg(OH) 2 (s)
• Mg(OH) 2 (s) + 2HCl(aq) -> MgCl 2 (s) + 2H 2 O(l)
• The MgCl 2 is then electrolyzed, yielding magnesium metal and chlorine gas.
• Calcium is in several important compounds, such as limestone (CaCO 3 ), gypsum (CaSO 4 ·2H 2 O), lime (CaO), and calcium silicate glass (CaSiO 3 ).
• Calcium hydroxide (Ca(OH) 2 ) is a key component of mortar. Calcium hydroxide is also used in water softeners to remove calcium bicarbonate (Ca(HCO 3 ) 2).
• Ca(HCO 3 ) 2 (aq) + Ca(OH) 2 (aq) -> 2CaCO 3 (s) + 2H 2 O(l)
• Calcium is found in teeth in the form of apatite
  (Ca 5 (PO 4 ) 3 OH).
• Barium sulfate emulsions are used to visualize organs, such as the stomach, with x rays.

Question 3

Which process is used to isolate magnesium from seawater?

Answer 3

Dow process

Question 4

What is the third most common element in seawater?

Answer 4

Magnesium

Question 5

Which of the following statements comparing the alkaline earth metals to the alkali metals is incorrect?

Answer 5

Alkaline earth metals form 1+ cations, while the alkali metals form 2+ cations.

Question 6

Which of the following statements best explains why fluorine is a strong oxidant and barium is a weak oxidant?

Answer 6

F is highly electronegative and Ba is not very electronegative

Question 7

Which of the following is not a common application of magnesium?

Answer 7

Fire extinguisher

Question 8

Which of the following equations correctly describes the water softening process?

Answer 8

Ca2+(aq) + 2HCO3- (aq) + Ca2+(aq) + 2OH-(aq) -> 2CaCO3(s) + 2H2O(l)

Question 9

Arrange the steps of the Dow process of magnesium isolation in the correct order:

1. Mg(OH)2 + HCl -> MgCl2 + 2H2O
2. Mg2+ + 2OH- -> Mg(OH)2
3. CaO + H2O -> Ca(OH)2
4. MgCl2(l) -> Mg(s) + Cl2(g)

Answer 9

3, 2, 1, 4

Question 10

Which of the following alkaline earth metal compounds is amphoteric?

Answer 10

Be(OH)2

Question 11

Which of the following ores or minerals contains two different alkaline earth metals?

Answer 11

Dolomite

Question 12

Calcium is found in teeth as which mineral?

Answer 12

Hydroxyapatite