📝 Detailed Notes on Chemistry of Group 2 Elements for JEE Preparation

1. Physical Properties

• Crystal structure and atomic radii: Calcium, strontium, barium, and radium have a body-centered cubic (bcc) crystal structure, while beryllium and magnesium have a hexagonal close-packed (hcp) structure. Atomic radii increase down the group due to the increase in the number of energy levels.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

• Melting and boiling points: Melting and boiling points increase down the group. This is because the strength of the metallic bond increases down the group due to the increase in the number of valence electrons.

Reference: NCERT 12th, Chapter 8, “The d and f-Block Elements”

• Density and hardness: Density increases down the group, while hardness decreases. This is because the atomic mass increases down the group, while the metallic bond strength decreases.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

• Color and luster: Beryllium and magnesium are silvery-white, while calcium, strontium, barium, and radium are whitish-yellow. All group 2 elements have a metallic luster.

Reference: NCERT 12th, Chapter 8, “The d and f-Block Elements”

• Ionization energy and electron affinity: Ionization energy decreases down the group, while electron affinity increases. This is because the number of valence electrons increases down the group, making it easier to remove electrons and harder to add electrons.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

2. Chemical Properties

• Reactivity with air and water: Beryllium and magnesium react slowly with air to form a layer of oxide on their surface. Calcium, strontium, barium, and radium react more vigorously with air to form oxides, nitrides, and hydroxides. All group 2 elements react with water to form hydroxides.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

• Formation of oxides, hydroxides, and halides: Group 2 elements form oxides, hydroxides, and halides with the general formulas MO, M(OH)2, and MX2, respectively. The oxides and hydroxides are basic in nature, while the halides are ionic compounds.

Reference: NCERT 12th, Chapter 8, “The d and f-Block Elements”

• Thermal stability of compounds: The thermal stability of group 2 compounds decreases down the group. This is because the strength of the ionic bond decreases down the group due to the increase in the size of the ions.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

• Reducing properties: Reducing properties increase down the group. This is because the ionization energy decreases down the group, making it easier for group 2 elements to lose electrons.

Reference: NCERT 12th, Chapter 8, “The d and f-Block Elements”

• Complexation behavior: Group 2 elements form complexes with various ligands, such as EDTA, oxalate, and fluoride. The stability of the complexes increases down the group due to the increase in the size of the ions.

Reference: NCERT 12th, Chapter 9, “Coordination Compounds”

3. Group 2 Carbonates

• Preparation: Group 2 carbonates can be prepared by the reaction of group 2 elements or their oxides, hydroxides, or halides with carbon dioxide gas.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

• Properties: Group 2 carbonates are white solids that are insoluble in water. They decompose on heating to form the corresponding oxide and carbon dioxide gas.

Reference: NCERT 12th, Chapter 8, “The d and f-Block Elements”

• Uses: Group 2 carbonates are used in various industries, such as:
  • The manufacture of cement.
  • The production of glass.
  • As a flux in metallurgy.
  • In the food industry as preservatives and antacids.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

4. Group 2 Sulfates

• Preparation: Group 2 sulfates can be prepared by the reaction of group 2 elements or their oxides, hydroxides, or halides with sulfuric acid.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

• Properties: Group 2 sulfates are white solids that are soluble in water. They decompose on heating to form the corresponding oxide and sulfur dioxide gas.

Reference: NCERT 12th, Chapter 8, “The d and f-Block Elements”

• Uses: Group 2 sulfates are used in various industries, such as:
  • The manufacture of fertilizers.
  • The production of paper.
  • As a mordant in dyeing.
  • In the food industry as preservatives and flavor enhancers.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

5. Group 2 Nitrates

• Preparation: Group 2 nitrates can be prepared by the reaction of group 2 elements or their oxides, hydroxides, or halides with nitric acid.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

• Properties: Group 2 nitrates are white solids that are soluble in water. They decompose on heating to form the corresponding oxide and nitrogen dioxide gas.

Reference: NCERT 12th, Chapter 8, “The d and f-Block Elements”

• Uses: Group 2 nitrates are used in various industries, such as:
  • The manufacture of fertilizers.
  • The production of explosives.
  • As a oxidizing agent in metallurgy.
  • In the food industry as preservatives and flavor enhancers.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

6. Group 2 Halides

• Preparation: Group 2 halides can be prepared by the reaction of group 2 elements or their oxides, hydroxides, or carbonates with hydrogen halide gas.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

• Properties: Group 2 halides are white solids that are soluble in water. They are ionic compounds and have high melting and boiling points.

Reference: NCERT 12th, Chapter 8, “The d and f-Block Elements”

• Uses: Group 2 halides are used in various industries, such as:
  • The manufacture of plastics.
  • The production of glass.
  • As a flux in metallurgy.
  • In the food industry as preservatives and flavor enhancers.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

7. Biological Significance

• Calcium: Calcium is the most abundant group 2 element in the body. It is essential for the formation of bones and teeth, muscle contraction, and nerve transmission.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

• Magnesium: Magnesium is the second most abundant group 2 element in the body. It is involved in numerous biochemical reactions, including energy metabolism, protein synthesis, and muscle contraction.

Reference: NCERT 12th, Chapter 8, “The d and f-Block Elements”

• Strontium and barium: Strontium and barium are trace elements in the body. Strontium is involved in the formation of bones and teeth, while barium is involved in the regulation of muscle contraction.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

8. Industrial Applications

• Metallurgy: Group 2 elements are used as reducing agents in the extraction of metals from their ores. For example, calcium is used in the extraction of uranium, thorium, and zirconium from their ores.

Reference: NCERT 12th, Chapter 8, “The d and f-Block Elements”

• Glass and cement manufacturing: Group 2 elements are used in the manufacture of glass and cement. For example, calcium carbonate is used in the production of Portland cement, while magnesium sulfate is used in the production of float glass.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

• Pharmaceuticals: Group 2 elements are used in the manufacture of various pharmaceutical products. For example, calcium carbonate is used as an antacid, while magnesium sulfate is used as a laxative.

Reference: NCERT 12th, Chapter 8, “The d and f-Block Elements”

• Agriculture: Group 2 elements are essential for plant growth. Calcium is a component of the cell wall, while magnesium is involved in photosynthesis.

Reference: NCERT 11th, Chapter 10, “The s-Block Elements”

9. Environmental Impact

• Air pollution: Calcium carbonate dust can cause air pollution, which can lead to respiratory problems.

_Reference: NCERT 11th, Chapter 10, “The s