Chem

Properties of Metals and Their Uses

1. Gold (Au)

• Appearance: Shiny yellow metal, precious due to beauty, scarcity, and stability.

• Properties: Chemically stable, does not react easily, malleable, resistant to corrosion, excellent conductor of electricity.

• Uses:

  • Making jewellery and coins.

  • Manufacturing electronic devices (computers, telephones, home appliances).

  • Dentistry (filling teeth cavities in alloy form).

• Purity: Pure gold (24 carat), often alloyed with copper or silver for strength (22 carat in India).

2. Silver (Ag)

• Appearance: Greyish-white, lustrous metal.

• Properties: Highly malleable, ductile, and the best conductor of heat and electricity.

• Uses:

  • Jewellery and coins.

  • Filling teeth cavities (alloyed form).

  • Water purification, electrode metal, electroplating.

  • Photography (silver bromide, silver nitrate).

  • Decoration (thin sheets for sweets).

3. Iron (Fe)

• Properties: Most useful and inexpensive metal. Typically reactive, found in combined states.

• Uses:

  • Construction (pipes, tanks, nails, agricultural tools, machinery).

  • Steel production (high tensile strength alloy with carbon).

  • Surgical instruments, utensils (stainless steel).

4. Copper (Cu)

• Appearance: Reddish-brown metal.

• Properties: Ductile and excellent conductor of heat and electricity.

• Uses:

  • Electric wires, coils, cables, utensils, semi-precious ornaments.

  • Coins and statues (bronze, brass alloys).

  • Electronic devices.

5. Aluminium (Al)

• Appearance: Silvery-white and soft metal, most abundant in Earth's crust.

• Properties: Malleable, ductile, and good conductor of heat.

• Uses:

  • Electric cables and wires (more affordable than copper).

  • Making utensils, furniture, cans, packaging (aluminium foil).

  • Alloyed for strength in aircraft, tools, machine parts (e.g., duralumin).

6. Zinc (Zn)

• Appearance: Bluish-white metal.

• Properties: Brittle, not malleable or ductile.

• Uses:

  • Electrode metal, creating brass and bronze alloys, dry cells.

  • Galvanization for rust protection of iron sheets.

7. Mercury (Hg)

• Appearance: Silvery-white liquid metal.

• Uses:

  • Thermometers, barometers.

  • Dentistry (silver amalgam, gold amalgam).

8. Tin (Sn)

• Appearance: Silvery-white metal.

• Properties: Highly malleable, resistant to rust.

• Uses:

  • Food canning, preservation, and tinning of utensils.

  • Tin-plated iron sheets for boxes.

9. Magnesium (Mg)

• Appearance: Available in ribbon form.

• Uses:

  • Fireworks (burns brilliantly), making alloys (magnalium, duralumin).

  • Vital for plant life (chlorophyll pigment).

10. Lead (Pb)

• Appearance: Heavy, silvery-grey metal.

• Uses:

  • Storage batteries, sanitary pipes, roof materials, solder (50% tin and 50% lead).

11. Platinum (Pt)

• Appearance: Lustrous and precious.

• Properties: Chemically inert like gold.

• Uses:

  • Making electrodes, expensive jewellery, catalysts in chemical processes.

12. Tungsten (W)

• Appearance: Shiny grey metal.

• Properties: Highest melting point among metals, resistant to acids.

• Uses:

  • Electrodes, heating elements, electric bulbs as filaments.

  • Heavy metal alloys for cutting tools.

Properties and Uses of Non-metals

1. Oxygen (O2)

• Uses:

  • Essential for respiration in humans and animals.

2. Carbon (C)

• Main forms: Coal, graphite, and diamond.

  • Coal: Used as fuel and in manufacturing textiles and pharmaceuticals.

  • Graphite: Used in pencils, lubricants, and nuclear reactors due to its conductivity.

  • Diamond: Valuable in jewellery, and useful for cutting glass.

3. Iodine (I2)

• Uses:

  • Largely for human growth (iodized salt).

  • Photography and antiseptics (tincture of iodine).

4. Chlorine (Cl2)

• Uses:

  • Disinfecting water, manufacturing insecticides, and bleach.

5. Hydrogen (H2)

• Uses:

  • Production of ammonia, hydrogenation in oils.

6. Sulphur (S)

• Uses:

  • Manufacture of rubber products, fungicides, sulphuric acid.

Metalloids

• Definition: Elements exhibiting properties of both metals and non-metals.

• Examples: Silicon, germanium, arsenic, etc.

Uses of Some Metalloids

1. Silicon (Si)

• Attributes: Abundant, utilized in electronics and optics, e.g., microchips.

2. Germanium (Ge)

• Utilized as a semiconductor, especially in electronics.

3. Antimony (Sb)

• Utilized in batteries and semiconductor devices.

Inert or Noble Gases

• Definition: Non-reactive gases that do not combine with other elements.

• Examples: Helium, neon, argon, krypton, xenon, and radon.

Uses of Inert Gases

1. Helium (He)

• Used in balloons for weather observations

2. Argon (Ar)

• Used in electric bulbs to prolong filament life.

3. Neon (Ne)

• Used in illuminated signs.

Corrosion in Metals

Overview

• Definition: The degradation of metals when exposed to moisture and air, leading to alterations in properties.

Example - Rusting of Iron

• Formation: Iron reacts with oxygen with moisture producing rust (hydrated ferric oxide, Fe2O3 ullet xH_2O) as a flaky brown substance.

• Process:

  • 4Fe + 3O2 + xH2O
    ightarrow 2Fe2O3 ullet xH_2O

• Economic Impact: Rust severely weakens metal structures and leads to economic loss.

Conditions for Rusting

• Necessary components: Air (oxygen) and moisture.

• Test (Activity 12): Nails in contact with both air and water rust; other test tubes with either air or water remain rust-free.

Prevention Techniques

• Methods:

  • Painting: Coatings on iron parts (e.g., red lead).

  • Oiling/Greasing: Protective lubricants.

  • Galvanization: Dipping in zinc to create a protective layer.

• Examples:

  • Tin Plating: Non-toxic tin coatings for food packaging.

  • Aluminium Coating: To protect structures from corrosion.

Importance of Prevention

• Essential for maintaining the utility and longevity of iron and its products in various applications.