Earth’s Elemental Composition

Common Elements in the Universe

• Hydrogen and Helium: Most abundant elements in the universe.
  • Other elements are produced in stars and distributed after they die.

Elemental Composition of Earth

• Helium: Very little found on Earth.
• Hydrogen: Not found in elemental form, usually in compounds.

Earth’s Structure and Elemental Distribution

• Differentiation Process: Earth materials separated by density.
  • Denser materials sank; less dense materials rose.
  • Resulted in Earth’s layered structure.

Layers of Earth

1. Core

   • Radius: ~3400 km.
   • Composition: Predominantly iron and nickel, with some transition metals.
   • Inner Core: Solid.
   • Outer Core: Liquid.

2. Mantle

   • Contains metal silicates.
   • Less dense than the core.

3. Crust

   • Lithosphere: Rocks and soil.
   • Hydrosphere: Oceans.
   • Atmosphere: Gases.

Elemental Distribution

• Core Elements: Transition metals (high density).
• Sulfide Phase: Lower density elements.
• Silicate Phase: Dominant in the crust.
• Atmosphere Elements: Mainly nitrogen, oxygen, argon.
• Scarce Elements: Elements in white on the periodic table, often created artificially.

Abundance of Elements in Earth's Crust

• Iron: Most abundant at 31.9%, major part of the core.
• Oxygen: Abundant in mantle and crust, in many silicates.
• Silicon: Found in silicates.
• Magnesium: Common after silicon.
• Other Elements: Less than 1% abundance.
• Helium: Almost negligible presence on Earth.

Conclusion

• Rarity of materials affects their value, often due to scarcity in the Earth's composition.