Chemistry revision for AQA Core science Chemicstry !B

1. The earth’s structure

2. The Earth has a layered structure. Large-scale movements of the Earth’s crust can cause changes in the rocks. The Earth’s atmosphere was originally very different from what it is today. It has been much the same for the last 200 million years and provides the conditions needed for life on Earth. Recently human activities have produced further changes.

3. Aims to explain why the theory of crustal movement (continental drift) was not generally accepted for many years after it was proposed to explain why scientists cannot accurately predict when earthquakes and volcanic eruptions will occur to explain and evaluate theories of the changes that have occurred and are occurring in the Earth’s atmosphere to explain and evaluate the effects of human activities on the atmosphere.

4. • The Earth consists of a core, mantle and crust.

5. • Scientists once thought that the features of the Earth’s surface were the result of the shrinking of the crust as the Earth cooled down following its formation.

6. • The Earth’s crust and the upper part of the mantle are cracked into a number of large pieces (tectonic plates). Convection currents within the Earth’s mantle, driven by heat released by natural radioactive processes, cause the plates to move at relative speeds of a few centimetres per year.

8. Pieces fitted together like jigsaw

9. Matching layers in the rocks of the different continents

12. Wegener thought the continents were ploughing through the ocean causing tidal forces – other geologists said this was impossible

13. Wegener used inaccurate data in his calculations – some of his predictions were rather wild

14. In the 1950s ocean floor investigations found evidence to support Wegener’s theory.

16. • For 200 million years, the proportions of different gases in the atmosphere have been much the same as they are today: − about four-fifths (78%) nitrogen − about one-fifth (21%) oxygen − small proportions of various other gases, including carbon dioxide, water vapour and noble gases.

17. • The noble gases are in Group 0 of the periodic table. They are all chemically unreactive gases and are used in filament lamps and electric discharge tubes. Helium is much less dense than air and is used in balloons.

18. • During the first billion years of the Earth’s existence there was intense volcanic activity. This activity released the gases that formed the early atmosphere and water vapour that condensed to form the oceans.

20. • Most of the carbon from the carbon dioxide in the air gradually became locked up in sedimentary rocks as carbonates and fossil fuels.

21. • Nowadays the release of carbon dioxide by burning fossil fuels increases the level of carbon dioxide in the atmosphere

23. • The Earth consists of a _______, _______and _______.

24. • Scientists once thought that the features of the Earth’s surface were the result of the shrinking of the crust as the Earth cooled down following its formation.

25. • The Earth’s crust and the upper part of the mantle are cracked into a number of large pieces (_________). Convection currents within the Earth’s mantle, driven by heat released by natural radioactive processes, cause the plates to move at relative speeds of a few _________ per ________.

27. Pieces fitted together like ________

28. Matching ________ in the rocks of the different _________

31. Wegener thought the continents were ploughing through the ocean causing ________– other geologists said this was ________

32. Wegener used ___________in his calculations – some of his predictions were rather wild

33. In the 1950s __________________found evidence to support Wegener’s theory.

35. • For _______years, the proportions of different gases in the atmosphere have been much the same as they are today: − about ________ (____%) nitrogen − about _________(____%) oxygen − small proportions of various other gases, including ___________, _________ and ______ gases.

36. • The _______are in Group __ of the periodic table. They are all chemically ________ gases and are used in _________ and _______tubes. ______ is much less dense than air and is used in _________.

37. • During the first billion years of the Earth’s existence there was intense _____ activity. This activity released the gases that formed the early atmosphere and water vapour that condensed to form the ________.

39. • Most of the carbon from the _________in the air gradually became locked up in sedimentary ______ as carbonates and ________.

40. • Nowadays the release of _________by burning _________ increases the level of _________ in the atmosphere