Questions and Answers
What is the other name for group 2 metals and why?
Alkaline earth metals, because their oxides and hydroxides are alkaline.
What are some uses of group 2 metals?
Beryllium alloys and magnesium alloys in aerospace; calcium carbonate in cement; strontium compounds in fireworks; barium in medicinal x-rays.
How many electrons do group 2 metals have in their outer shell, and which orbital is occupied?
Two electrons in the outer s-orbital.
Explain the trend in atomic radius as you go down group 2.
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Explain the trend in first ionisation energy as you go down group 2.
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Explain the trend in melting and boiling point as you go down the group.
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Explain the trend in electronegativity as you go down the group.
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What is the trend in reactivity when group 2 metals react with water?
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Explain the reaction of group 2 metals and water.
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What are the observations when group 2 metals (Mg->) react with water?
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Explain the trend in group 2 metal's reactivity with water.
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Which group of metals is more reactive?
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What is the trend in solubility of group 2 metal hydroxides?
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List the solubility of group 2 hydroxides from Mg->.
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What is the use of magnesium hydroxide?
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What is the use of calcium hydroxide?
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What is the trend in group 2 metal sulfates solubility?
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Give the solubilities of group 2 metal sulfates from Mg->.
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What is the test for sulfate ions?
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What is the use of barium sulfate?
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Give an overview of using magnesium to extract titanium.
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Explain the steps in which titanium is extracted by magnesium.
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Why is titanium expensive?
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Sulfur dioxide removal using CaO or CaCO3.
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What is wet scrubbing?
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Study Notes
Group 2: Alkaline Earth Metals
- Group 2 metals are referred to as alkaline earth metals because their oxides and hydroxides produce alkaline solutions.
- These metals belong to the s-block of the periodic table.
Uses of Group 2 Metals
- Beryllium and Magnesium alloys are lightweight and strong, making them essential in aerospace applications.
- Calcium carbonate is crucial for producing cement, concrete, and steel.
- Strontium compounds produce a crimson flame and are used in fireworks and tracer bullets.
- Barium carbonate is toxic, while barium sulfate is safe for medical X-rays due to its insolubility.
Electron Configuration
- All group 2 metals have two electrons in their outer s-orbital.
Trends in Atomic Radius
- Atomic radius increases down the group due to more occupied electron shells and greater electron shielding.
Trends in Ionization Energy
- The first ionization energy decreases down the group because the outer electron is easier to remove as it is found on higher energy levels, facing increased shielding.
Trends in Melting and Boiling Points
- Melting and boiling points generally decrease down the group due to the weakening metallic bonds as the ionic radius increases.
- A notable discontinuity exists between magnesium and calcium due to different crystal structures.
Trends in Electronegativity
- Electronegativity decreases down the group; beryllium shows covalent behavior, while heavier elements exhibit ionic characteristics due to larger ionic radii.
Reactivity with Water
- Group 2 metals increase in reactivity with water down the group, driven by the ease of losing outer electrons.
Reactions of Metals with Water
- Group 2 metals undergo redox reactions with water, forming metal hydroxides and hydrogen gas.
- Magnesium reacts slowly with cold water but rapidly with steam to produce magnesium oxide.
Specific Reactions
- Calcium, strontium, and barium react vigorously with cold water, producing hydroxides and hydrogen gas.
- Beryllium does not react with water due to high second ionization energy.
Observations During Reactions
- Effervescence (bubbles from hydrogen gas) and a color change with universal indicator indicate hydroxide formation during the reaction of group 2 metals with water.
Solubility Trends
- Solubility of group 2 metal hydroxides increases down the group, while sulfate solubility decreases.
- Magnesium hydroxide is sparingly soluble, calcium hydroxide is slightly soluble, strontium hydroxide is more soluble, and barium hydroxide dissolves to create a strongly alkaline solution.
Applications of Hydroxides
- Magnesium hydroxide is used as an antacid (milk of magnesia) and in toothpaste.
- Calcium hydroxide (lime water) is utilized in agriculture to adjust soil pH.
Extraction of Titanium
- Titanium is extracted via magnesium due to the formation of titanium carbide when using carbon.
- The extraction process begins by converting TiO2 to TiCl4, chemical purification is achieved, then conversion back to titanium occurs at high temperatures.
Cost Factors in Titanium Extraction
- High cost stems from magnesium, batch processing, and stringent conditions (inert atmosphere and high temperatures).
Sulfur Dioxide Mitigation
- Sulfur dioxide, a contributor to acid rain, can be reduced by scrubbing flue gases from coal-burning power stations through reactions with calcium oxide or calcium carbonate.
Wet Scrubbing Method
- Wet scrubbing techniques involve reacting sulfur dioxide with sea water or an alkaline slurry formed from calcium oxide to produce calcium sulfate, which is then removed as a solid.
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Description
Test your knowledge on group 2 metals, also known as alkaline earth metals. This quiz covers their properties, alternative names, and uses. Refresh your understanding and learn more about these essential elements.
