Metals and Their Compounds

Metals are elements characterized by their ability to lose electrons to form positive ions (cations). They occupy the left and middle portions of the periodic table.

1. General Properties of Metals

• Physical: High electrical and thermal conductivity, malleability, ductility, high melting points, and metallic luster.
• Chemical: They are electropositive, form basic oxides, and act as reducing agents.

2. Alkali Metals (Group 1) - Sodium

Sodium is highly reactive and found as NaCl in sea water. It is extracted by the Downs Process (electrolysis of molten NaCl).

• Sodium Hydroxide (NaOH): Produced by the electrolysis of brine. It reacts with amphoteric metals like Al, Zn, and Pb to form soluble complexes (e.g., Sodium aluminate).
• Solvay Process: Used to manufacture Sodium trioxocarbonate (IV) (Na2CO3). Raw materials: Ammonia, Brine, and Limestone.
• Uses: Na2CO3 is used in glass making and water softening. NaHCO3 is used in baking powder.

3. Alkaline-Earth Metals (Group 2) - Calcium

Calcium is found in limestone and sea shells. Calcium Oxide (CaO), or quicklime, is produced by the thermal decomposition of CaCO3.

• Cement: A mixture of calcium compounds (limestone) and aluminum silicates (clay).
• Mortar: A mixture of slaked lime, sand, and water which sets by absorbing CO2 from the air.

4. Aluminum

The main ore is Bauxite. Purification involves the Bayer Process to get pure Alumina (Al2O3). Extraction is done via the Hall-Héroult process (electrolysis of Al2O3 in molten Cryolite). Cryolite lowers the melting point and improves conductivity.

5. Transition Metals

Elements in the d-block (Sc to Zn). Characteristics include:

• Variable oxidation states (due to the proximity of 4s and 3d energy levels).
• Formation of colored ions (d-d electron transitions).
• Formation of complex ions (e.g., [Cu(NH3)4]2+).
• Catalytic properties.
• Paramagnetism (presence of unpaired electrons).

6. Iron and Copper

• Iron: Extracted in the Blast Furnace from Haematite (Fe2O3) using Coke as a reducing agent and Limestone as a flux to remove SiO2 as slag (CaSiO3).
• Copper: Extracted from Chalcopyrite (CuFeS2). Purified by electrolysis. Copper(II) tetraoxosulphate(VI) is prepared by reacting CuO or CuCO3 with H2SO4.

7. Alloys

Alloys are metallic mixtures that often have superior properties (strength, corrosion resistance) compared to pure metals.

• Brass: Cu + Zn
• Bronze: Cu + Sn
• Duralumin: Al + Cu + Mg + Mn
• Steel: Fe + C
• Stainless Steel: Fe + C + Cr + Ni
• Soft Solder: Pb + Sn