Earth's Crust
* Most Abundant:
* Oxygen (O): 46.6% by weight. Found in minerals like silicates and oxides.
* Silicon (Si): 27.7% by weight. Forms the backbone of most rocks and minerals.
* Aluminum (Al): 8.1% by weight. A common component of clays and feldspars.
* Iron (Fe): 5.0% by weight. Found in various minerals, often associated with oxygen.
* Calcium (Ca): 3.6% by weight. Found in limestone, gypsum, and other minerals.
* Sodium (Na): 2.8% by weight. Present in various minerals like feldspar and halite.
* Potassium (K): 2.6% by weight. Found in minerals like feldspar and mica.
* Magnesium (Mg): 2.1% by weight. Found in minerals like olivine and dolomite.
* Other Important Elements:
* Titanium (Ti)
* Hydrogen (H)
* Phosphorus (P)
* Manganese (Mn)
* Sulfur (S)
* Chlorine (Cl)
Earth's Oceans
* Most Abundant:
* Oxygen (O): 85.84% by weight. Part of water molecules (H₂O).
* Hydrogen (H): 10.82% by weight. Part of water molecules (H₂O).
* Chlorine (Cl): 1.94% by weight. Found as dissolved salts.
* Sodium (Na): 1.07% by weight. Found as dissolved salts.
* Magnesium (Mg): 0.13% by weight. Found as dissolved salts.
* Sulfur (S): 0.09% by weight. Found as dissolved salts.
* Calcium (Ca): 0.04% by weight. Found as dissolved salts.
* Potassium (K): 0.04% by weight. Found as dissolved salts.
* Other Elements:
* Bromine (Br): Found in dissolved salts.
* Carbon (C): Found in dissolved organic compounds.
* Nitrogen (N): Found in dissolved gases.
* Trace amounts of many other elements.
Earth's Atmosphere
* Most Abundant:
* Nitrogen (N): 78.08% by volume. An inert gas, essential for life processes.
* Oxygen (O): 20.95% by volume. Essential for respiration and combustion.
* Argon (Ar): 0.93% by volume. An inert gas.
* Other Elements:
* Carbon dioxide (CO₂): A greenhouse gas, important for regulating Earth's temperature.
* Water vapor (H₂O): Varies in concentration depending on location and weather conditions.
* Neon (Ne): An inert gas.
* Helium (He): An inert gas.
* Methane (CH₄): A greenhouse gas, linked to human activity.
* Ozone (O₃): A gas that absorbs harmful ultraviolet radiation from the sun.
* Trace amounts of other elements and compounds.
Key Points to Remember:
* The relative abundance of elements varies greatly between these layers.
* This is a simplified overview. Each layer contains many other elements in trace amounts.
* The Earth's composition has changed over geological time.
