Chemistry of the atmosphere - Paper 2

What are the main gases in Earth’s atmosphere?

: Nitrogen (≈78%), oxygen (≈21%), argon (≈1%), carbon dioxide (≈0.04%)

How was the Earth’s early atmosphere formed?

From gases released by volcanic activity (mainly carbon dioxide, water vapour, and nitrogen).

Why did CO2 levels decrease over time?

It dissolved in oceans, formed sedimentary rocks, and was used by plants in photosynthesis.

How did O2 levels in the atmosphere increase?

Through photosynthesis by algae and plants.

What is photosynthesis?

The process where plants use carbon dioxide and water to produce glucose and oxygen using sunlight.

What is the greenhouse effect?

The trapping of heat by greenhouse gases, keeping Earth warm enough to support life.

Name two greenhouse gases?

CO2 and Methane

What causes increased levels of CO2 in the atmosphere?

Burning fossil fuels and deforestation

What is global warming?

The increase in Earth’s average temperature due to increased greenhouse gases.

How can humans reduce climate change?

Using renewable energy, reducing fossil fuel use, and planting trees