Metals And Non-Metals

Elements are broadly classified into metals and non-metals based on their properties. This classification helps predict the behaviour of elements during chemical reactions and their applications across various industries.

1.0What are Metals?

Metals are elements that readily lose electrons to form positive ions (cations) and possess high electrical and thermal conductivity. They are typically malleable, ductile, and have a shiny appearance.

2.0Physical Properties of Metals

• Lustre: Metals have a shiny surface when freshly cut.
• Malleability: They can be hammered into thin sheets without breaking.
• Ductility: Metals can be drawn into thin wires.
• Conductivity: They are good conductors of heat and electricity.
• Density and Melting Point: Metals generally have high densities and melting points.
• State at Room Temperature: Most metals are solid at room temperature, except for mercury, which is liquid.

3.0Chemical Properties of Metals

• Reaction with Oxygen: Metals react with oxygen to form metal oxides, which are usually basic in nature.
• Example: 4Na + O₂ → 2Na₂O
• Reaction with Water: Some metals react with water to produce metal hydroxides and hydrogen gas.
• Example: 2Na + 2H₂O → 2NaOH + H₂↑
• Reaction with Acids: Metals react with acids to form salt and hydrogen gas.
• Example: Zn + 2HCl → ZnCl₂ + H₂↑
• Electropositivity: Metals tend to lose electrons easily, forming positive ions.

4.0What are Non-Metals?

Non-metals are elements that tend to gain electrons to form negative ions (anions) and are poor conductors of heat and electricity. They are generally brittle and lack luster.

5.0Physical Properties of Non-Metals

• Lack of Lustre: Non-metals do not have a shiny appearance.
• Brittleness: They are brittle and break easily when subjected to stress.
• Poor Conductivity: Non-metals are poor conductors of heat and electricity, with the exception of graphite.
• Low Density and Melting Point: They generally have lower densities and melting points compared to metals.
• State at Room Temperature: Non-metals can exist in all three states: solid (e.g., sulfur), liquid (e.g., bromine), and gas (e.g., oxygen).

6.0Chemical Properties of Non-Metals

• Reaction with Oxygen: Non-metals react with oxygen to form acidic or neutral oxides.
• Example: C + O₂ → CO₂
• Reaction with Water: Non-metals do not react with water in the same way metals do; however, some non-metal oxides can dissolve in water to form acids.
• Example: CO₂ + H₂O → H₂CO₃
• Reaction with Acids and Bases: Non-metals generally do not react with acids but can react with bases to form salts.
• Electronegativity: Non-metals have a high tendency to gain electrons, forming negative ions.

7.0Differences Between Metals and Non-Metals

8.0Metalloids: The Intermediate Elements

Metalloids are elements that exhibit properties intermediate between metals and non-metals. They are found along the zigzag line on the periodic table that separates metals and non-metals.

Examples of Metalloids:

• Silicon (Si): Used in semiconductors and electronics.
• Boron (B): Used in borosilicate glass and detergents.
• Arsenic (As): Used in pesticides and semiconductors.

Properties of Metalloids:

• Appearance: Generally metallic in appearance.
• Conductivity: Semiconductors; conductivity increases with temperature.
• Malleability and Ductility: Brittle like non-metals.

9.0Important Metallurgical Processes (Extraction of Metals)

Metallurgy is the process of extracting metals from their ores.

Concentration of Ores

• Gravity separation, Froth flotation, Magnetic separation, and Leaching are used depending on the ore type.

Roasting and Calcination

• Roasting: Heating sulphide ores in excess air.

$2\mathrm{ZnS}+3{\mathrm{O}}_2\to 2\mathrm{ZnO}+2{\mathrm{SO}}_2$

• Calcination: Heating carbonate ores in limited air.

${\mathrm{CaCO}}_3\to \mathrm{CaO}+{\mathrm{CO}}_2$

Reduction Methods

• Smelting with Carbon:

${\mathrm{Fe}}_2{\mathrm{O}}_3+3\mathrm{C}\to 2\mathrm{Fe}+3\mathrm{CO}$

• Thermite Reaction (Highly exothermic):

${\mathrm{Fe}}_2{\mathrm{O}}_3+2\mathrm{Al}\to 2\mathrm{Fe}+{\mathrm{Al}}_2{\mathrm{O}}_3$

Electrolytic Reduction

• Highly reactive metals (Na, K, Al) are extracted by electrolysis of molten salts.
• Example: Electrolysis of molten NaCl produces Na and Cl₂ gas.

10.0Applications of Metals and Non-Metals

Metals:

• Construction: Iron and steel are used in building infrastructure.
• Electrical Wiring: Copper and aluminium are used due to their high conductivity.
• Transportation: Aluminium is used in aircraft; steel is used in automobiles.
• Jewellery: Gold and silver are used for ornaments.

Non-Metals:

• Medicine: Oxygen is essential for respiration; iodine is used as an antiseptic.
• Agriculture: Nitrogen is a key component of fertilizers.
• Water Purification: Chlorine is used to disinfect water.
• Fuel: Hydrogen is used in fuel cells; carbon is a major component of fossil fuels.