Earth and Environmental

List the elements that make up the composition of the Earth’s atmosphere from largest percentage to smallest.

1. Nitrogen

2. Oxygen

3. Argon

4. Carbon dioxide

5. Water vapour

6. Ozone

List the steps of volcanic outgassing.

1. Magma formation - Gases dissolve in molten rock deep underground

2. Volcanic eruption - Pressure decreases as magma rises

3. Gas release - CO2 (carbon dioxide), H2O (water), and N2 (nitrogen) enter the atmosphere

4. Atmospheric accumulation - Gases build up over millions of years

What was the role of volcanic outgassing in the origin of Earth’s atmosphere?

Volcanic outgassing was the primary contributor of early gases.

List the main gases released by volcanic outgassing.

Water vapour, carbon dioxide, and sulfur dioxide.

Describe the decrease in carbon dioxide levels 2 billion years ago.

The accumulation of carbon dioxide increased Earth’s temperature and melted ice into water. This water supported early life - photosynthetic organisms which used carbon dioxide and therefore removed it from the atmosphere.

What is the balanced chemical equation for photosynthesis?

6CO₂ + 6H₂O → C₆ H₁₂O₆ + 6O₂