Metals and Non Metals

Composition of Alloys

  • Duralumin
    • Composition:
    • $Al: 95\%$
    • $Cu: 4\%$
    • $Mg + Mn: 1\%$
    • Special Property:
    • Hard and tensile like steel, but very light in weight.
    • Uses:
    • Aircraft frames
    • Pressure cookers
    • Parts of automobiles

Interesting Facts

  • The Iron Pillar near Qutub Minar in Delhi is actually an alloy known as stainless steel.
    • It is resistant to:
    • Temperature change
    • Chemicals
    • Air
    • Water
    • Age: Approximately 1,600 years old.

Mercury and Its Compounds

  • Mercury and its compounds are highly poisonous.
  • Handling precautions: Must be done with great care.
  • Most metals dissolve in mercury:
    • The product formed is an amalgam, not an alloy.
    • Example: Sodium dissolving in mercury forms sodium amalgam.

Common Alloys and Their Properties

  1. Brass

    • Composition:
      • $Cu: 80\%$
      • $Zn: 20\%$
    • Special Property:
      • Yellow lustrous alloy, more malleable than copper, highly corrosion-resistant, tough, easy to mold.
    • Uses:
      • Utensils
      • Door handles, screws, nuts, bolts
      • Cartridges
      • Musical instruments (e.g., trumpets)
      • Decorative objects (e.g., vases, lamps)

  2. Duralumin

    • Composition:
      • Alloy of aluminum and copper with traces of manganese and magnesium

  3. Gold Alloy

    • Composition:
      • $Au: 92\%$
      • $Ag: 5\%$
      • $Cu: 2\%$
    • Special Property:
      • Hardness improved by alloying with metals like silver or copper; lower melting point than pure gold, takes good polish, easily molded.
    • Uses:
      • Jewelry, coins, watch cases, spectacle rims
      • Dentistry (to fill teeth cavities, manufacture parts of electronic devices)

  4. Bronze

    • Composition:
      • $Cu: 90\%$
      • $Sn: 10\%$
    • Special Property:
      • Hard, resistant to carbon dioxide and moisture in the air, high polish, easy to mold.
    • Uses:
      • Statues
      • Turbines
      • Coins, medals

  5. Stainless Steel

    • Composition:
      • $Fe: 75\%$
      • $Cr: 14\%$
      • $Ni: 10\%$
      • $C: 1\%$
    • Special Property:
      • Lustrous, strong, does not rust.
    • Uses:
      • Household utensils, cutlery
      • Surgical instruments

Metalloids and Their Uses

  • Definition: Metalloids are elements possessing properties of both metals and non-metals.
  • Uses:
    • Silicon:
    • Used in computer parts, alloyed with iron for electrical steel, and aluminium for automotive parts.
    • Germanium: Used in optic fibers.
    • Arsenic: Alloyed with lead in car batteries, germanium for high-speed integrated circuits and LEDs.
    • Antimony:
    • Its oxide is a flame retardant, alloyed with lead