Lecture Notes: Group Two Elements
Overview of Group Two Elements
- Elements: Beryllium, Magnesium, Calcium, Strontium, Barium, Radium
- Part of the S-block in the periodic table
Atomic Numbers
- Beryllium (4)
- Magnesium (12)
- Calcium (20)
- Strontium (38)
- Barium (56)
- Radium (88)
Trends and Properties
- Atomic and Ionic Radius
- Increase going down the group
- Decrease going across a period
- Density
- Increases going down the group
- Melting Points
- Decrease going down the group
- Ionization Energy
- First ionization energy decreases down the group
Chemical Reactions and Properties
- Reactivity
- Increases down the group
- Reacts with oxygen, water, and dilute acids
- Solubility of Sulfates
- Decreases going down the group
- Thermal Decomposition
- Stability increases down the group
Uses of Group Two Elements
- Magnesium and Calcium Compounds
- Magnesium oxide, calcium oxide, hydroxides, and carbonates used in daily practices
- Magnesium Uses
- Lightweight alloys, medication, laxatives
- Calcium Uses
- Construction, medical supplements, antacids, soil acidity control
- Barium Uses
- Barium meals, absorbs x-rays, used in fireworks
Key Concepts
- Lattice Energy vs. Hydration Energy
- Solubility is influenced by these energies
- Solubility decreases if lattice energy > hydration energy
- Polarization and Thermal Stability
- Smaller cations can polarize large anions, affecting stability
- Ionic characteristics increase with polarization
Reaction Details
- With Oxygen
- Forms metal oxides
- Exothermic reactions
- With Water
- Forms hydroxides and hydrogen gas
- Solubility of hydroxides increases down the group
- With Acids
- Forms salts and hydrogen gas
- Reactivity increases down the group
Additional Notes
- Fireworks
- Group two metals impart distinct colors: strontium (crimson), barium (green)
- Environmental Impact
- Used in industrial pollution control to prevent acid rain
This comprehensive coverage of the group two elements explores their trends, chemical reactions, uses, and environmental significance.