1.4 The ever-changing Earth

What are the 4 layers of the Earth?

1. Solid inner core

2. Liquid outer core

3. Mantle (has solid and liquid properties)

4. Solid crust

What layers of Earth make up the lithosphere?

Crust and upper mantle

What is the theory of plate tectonics?

1. The Earth's lithosphere is divided into separate parts known as tectonic plates.

2. These plates move over the mantle at a rate of a couple cm per year. This process is known as continental drift.

What was Alfred Wegener's early theory on continental drift?

The countries all used to be joined together in a super-continent called Pangea. The Earth's crust and mantle are made up of sections which drifted apart over millions of years.

What occurs at a conservative plate boundary?

1. Two plates slide past each other

2. If the movement is sudden and large enough then, there is an earthquake

3. No volcanoes are found at this boundary.

What occurs at a destructive plate boundary?

1. Two plates move towards each other

2. The denser plate is pushed beneath the other and melts

3. This forms magma, which rises up and leads to the formation of volcanoes and earthquakes

4. The magma cools forming new igneous rock.

What occurs at a constructive plate boundary?

1. Two plates move away from each other

2. Magma from the mantle rises up and forms new rock to fill the gap created

3. If the pressure is high enough, a volcanic eruption may occur.

How was the early atmosphere formed?

The intense volcanic activity released gases such as carbon dioxide and water vapour.

What is the present composition of the atmosphere?

78% nitrogen

21% oxygen

< 1% other gases (argon, carbon dioxide & water vapour)

What are the causes which lead to the increase in atmospheric oxygen concentration?

1. Algae and plants release oxygen into the atmosphere during photosynthesis

2. As plants evolve, concentration of oxygen increases, enabling animals to evolve and exist.

How has carbon dioxide concentration changed in the atmosphere?

1. Algae and plants decreases the carbon dioxide concentration in the atmosphere by using CO2 during photosynthesis

2. Formation of sedimentary rocks and fossil fuels which contain carbon decreases atmospheric CO2 levels

3. Atmospheric CO2 levels decreases as it dissolved in the ocean

How has the concentration of ammonia and methane in the atmosphere changed?

As oxygen levels increase:

1. Ammonia reacts with oxygen to form nitrogen and water

2. Methane reacts with oxygen to form carbon dioxide and water

Which 3 processes maintain oxygen and carbon dioxide levels in the atmosphere?

1. Combustion

2. Respiration

3. Photosynthesis

Why has the concentration of carbon dioxide in the atmosphere been increasing over the last century?

1. Deforestation

2. Increased burning of fossil fuels

3. Population growth

What is the major cause of climate change?

An increase in the levels of carbon dioxide and other greenhouse gases in the atmosphere.

What are the potential effects of global climate change?

1. Destruction of animal habitats that may cause extinction of species

2. Rising sea levels due to melting ice caps

3. Increased risk of skin cancer due to more exposure to UV rays

4. More extreme weather conditions ( e.g. droughts).

What is another byproduct of burning fuels other than carbon dioxide?

Sulfur dioxide

How is acid rain formed?

Sulfur dioxide released from burning fossil fuels dissolves in rainwater, forming sulfuric acid.

What are the effects of acid rain?

1. Damages buildings and statues made of limestone

2. Causes corrosion of metal

3. Reduces the growth of or kills trees and crops

4. Lowers pH of water in lakes, killing aquatic organisms

What measures are used to address the problems of global warming?

1. Reduce fossil fuel usage and use renewable sources instead

2. Encourage eco-friendly travel, recycling and reusing

3. Reforestation and creation of more green areas

4. International deals and targets for emissions between countries.

What measure is used to address acid rain?

Sulfur scrubbing- this technique removes 95% of sulfur dioxide from gases released by burning fuels.

Which elements can be found in the air?

1. Nitrogen

2. Oxygen

3. Neon

4. Argon

Describe the chemical test to identify oxygen gas.

A glowing splint will relight if placed into a test tube containing oxygen gas

Describe the chemical test to identify carbon dioxide.

When bubbled through lime water, carbon dioxide turns lime water cloudy.