Revision Flashcards
What gases are believed to have been released from volcanoes during the first billion years of the Earth’s existence?
Nitrogen, carbon dioxide, water vapour; small amounts of ammonia and methane.
How did the oceans form?
Water vapour in the atmosphere condensed.
Why did the amount of carbon dioxide in the earlier atmosphere decrease?
When oceans formed, carbon dioxide dissolved in the water; carbonates precipitated producing sediments, reducing carbon dioxide in the atmosphere.
How do you test for oxygen gas?
Glowing splint delights
What organisms increased the amount of oxygen in the Earth’s atmosphere?
Primitive plants/ algae.
Write the balanced symbol equation for photosynthesis.
6CO2 + 6H2O ——————> C6H12O6 + 6O2
Other than photosynthesis, what other factors decreased the level of carbon dioxide in the atmosphere?
Formation of sedimentary rocks and fossil fuels (natural gas, oil, coal).
Describe the main changes to the atmosphere over time and the likely causes of these changes.
Intense volcanic activity – water vapour, carbon dioxide, nitrogen, ammonia, methane released.
Water vapour condensed to form oceans.
Atmosphere mostly carbon dioxide; nitrogen slowly building up over time.
Carbon dioxide dissolved in oceans; carbonates precipitated producing sediments. Carbon dioxide levels in atmosphere drop.
Photosynthesis – algae produce oxygen.
Plants evolved, levels of carbon dioxide reduced, levels of oxygen increased; animals evolved.
Carbon dioxide levels dropped during the formation of sedimentary rock (from sediments) and fossil fuels (from organisms).
Name 3 greenhouse gases.
Water vapour, carbon dioxide, methane.
What is the link between greenhouse gases and the temperature of the Earth?
Greenhouse gases maintain temperatures on the Earth high enough to support life.
Name human activities which increase the amount of carbon dioxide in the atmosphere.
Burning/ combustion of fossil fuels, deforestation.
Name human activities that increase the amount of methane in the atmosphere.
Farming of livestock; landfill sites.
What do many scientists believe about human activities and the temperature of the Earth’s atmosphere?
Human activities will cause the temperature of the Earth’s atmosphere to increase at the surface resulting in climate change.
Why are there issues surrounding modelling human impact on climate change?
It is difficult to model these changes
There are uncertainties caused by the location where the measurements are taken.
Questions regarding historical accuracy.
Name two gases and their compositions in today’s atmosphere.
Nitrogen (80%), Oxygen (20%)
Place these metals in order of their reactivity:
Potassium, silver, copper, magnesium
Highest: Potassium, magnesium, copper, silver: lowest
Name the two non-metals in the reactivity series.
Carbon and hydrogen
Metals form positive ions. What is the scientific name for these positive ions?
Cations
Why is gold found in the Earth as an element rather than a compound?
It is very unreactive.
What is a redox reaction?
Reaction involving both oxidation and reduction.
Describe oxidation in terms of electrons.
oxidation is loss of electrons.
Describe reduction in terms of electrons.
reduction is gain of electrons.