iGCSE chemistry lesson 1

1. iGCSE chemistry lesson 1

2. Content The iGCSE Chemistry course Section 1 Principles of Chemistry Section 2 Chemistry of the Elements Section 3 Organic Chemistry Section 4 Physical Chemistry Section 5 Chemistry in Society

3. Content Section 1 Principles of Chemistry • States of matter • Atoms • Atomic structure • Relative formula mass • Chemical formulae and chemical equations • Ionic compounds • Covalent substances • Metallic crystals • Electrolysis

4. Content • Lesson 1 • States of matter • Atoms • Atomic structure 1.1 understand the arrangement, movement and energy of the particles in each of the three states of matter: solid, liquid and gas 1.2 describe how the interconversion of solids, liquids and gases are achieved and recall the names used for these interconversions 1.3 describe the changes in arrangement, movement and energy of particles during these interconversions.

5. What’s the difference?

6. What’s the difference?

7. Changes of State Gas Liquid Solid

8. Changes of State Gas Liquid { melting Solid

9. Changes of State Gas { Boiling (evaporating) Liquid { melting Solid

10. Changes of State Gas { } Boiling (evaporating) condensing Liquid { melting Solid

11. Changes of State Gas { } Boiling (evaporating) condensing Liquid { } melting freezing Solid

12. Changes of State Gas Liquid Particles are fixed in place and cannot move Solid

13. Changes of State Gas Particles are free to move within a container Liquid Particles are fixed in place and cannot move Solid

14. Changes of State Gas Particles are free to move about Particles are free to move within a container Liquid Particles are fixed in place and cannot move Solid

15. SOLIDS • Strong forces of attraction • held in fixed position • lattice arrangement • don’t move, so have definite shape and volume • vibrate

16. SOLIDS • as they become hotter, the particles vibrate more. • so they expand • can’t be compressed • generally very dense

17. SOLIDS • when heated, molecules gain energy. • they vibrate more and more • strong forces are overcome, molecules start to move = MELTED

18. LIQUIDS • Some attraction between molecules. • free to move • no definite shape, but take shape of container • molecules in constantly random motion

19. LIQUIDS • when heated, they move faster and expand • can’t be compressed • quite dense

20. LIQUIDS • heat makes the molecules move faster as they gain energy. • fast moving molecules at the surface will overcome forces of attraction and escape = EVAPORATION

21. GASES • no force of attraction • free to move, travel in straight lines • sometimes collide • no definite shape or volume, expand to fill space

22. GASES • exert pressure on wall of container • constantly moving randomly • move faster when heated • can be compressed • very low densities

23. GASES • when heated enough, molecules have enough speed and energy to overcome forces and escape each other. • molecules break away in big bubbles of gas = BOILING

24. Heating Temperature Gas Boiling point Liquid Melting point Solid Time

25. Cooling Temperature Gas Condensing Liquid Freezing Solid Time

26. Content • Lesson 1 • States of matter • Atoms • Atomic structure 1.4 describe simple experiments leading to the idea of the small size of particles and their movement including: i dilution of coloured solutions ii diffusion experiments 1.5 understand the terms atom and molecule 1.6 understand the differences between elements, compounds and mixtures 1.7 describe techniques for the separation of mixtures, including simple distillation, fractional distillation, filtration, crystallisation and paper chromatography.

27. Evidence of particles • Particles are very, very small, but what evidence do we have that they actually exist? • Two simple experiments help us to prove their existence: • Dilution of coloured solutions • Diffusion experiments

28. Dilution of coloured solutions Blue copper sulphate crystal

29. Dilution of coloured solutions Blue copper sulphate solution

30. Dilution of coloured solutions Dilution, 10cm3 copper sulphate solution + 90cm3 water

31. Dilution of coloured solutions Dilution, 10cm3 copper sulphate solution + 90cm3 water

32. Dilution of coloured solutions Dilution, 10cm3 copper sulphate solution + 90cm3 water

33. Dilution of coloured solutions Serial dilution of a solution such as copper sulphate provides evidence that the original crystal was made up of many small particles that spread out evenly when the solution is diluted by adding water.

34. Evidence of particles – diffusion experiments Spray air freshener in the corner of a room

35. Evidence of particles – diffusion experiments Particles spread out in all directions

36. Evidence of particles – diffusion experiments Eventually the particles occupy the whole room

37. Evidence of particles – diffusion experiments Other examples of diffusion include: Smell of frying bacon from a kitchen Leaking of air from inside a balloon Sugar dissolving in a cup of tea

38. Evidence of particles – diffusion experiments Diffusion is the movement of particles from areas of high concentration to areas of low concentration until they are evenly spread. Diffusion depends upon the random movement of particles.

39. Evidence of particles – diffusion experiments Diffusion is the movement of particles from areas of high concentration to areas of low concentration until they are evenly spread. Diffusion depends upon the random movement of particles. Diffusion is slower in liquids than in gases because liquid particles are not as free to move as gas particles.

40. Atoms and Molecules The basic building blocks of everything that we see in the Universe are atoms. The word ‘atom’ basically means ‘indivisible’.

41. Atoms and Molecules The basic building blocks of everything that we see in the Universe are atoms. The word ‘atom’ basically means ‘indivisible’. Combinations of atoms are called molecules. For example: O2 - a molecule of oxygen H2O - a molecule of water

42. Elements, mixtures and compounds

43. Elements, mixtures and compounds Cu Cu An element consists of one type of atom only. For example, pure copper consists of copper atoms only. Cu Cu Cu

44. Elements, mixtures and compounds S Fe Fe A mixture consists of different types of atoms that are not chemically bonded. S S S Fe

45. Elements, mixtures and compounds S Fe Fe A mixture consists of different types of atoms that are not chemically bonded. S S S Fe • Particles in a mixture can all be separated out quite easily. • No chemical bonds exist • Properties of the mixture are just a mixture of the properties of the separate parts.

46. Elements, mixtures and compounds S Fe In a compound the particles are held together by strong forces called chemical bonds. A chemical reaction will have taken place. Fe S C O O

47. Elements, mixtures and compounds S Fe In a compound the particles are held together by strong forces called chemical bonds. A chemical reaction will have taken place. Fe S C O O • Particles in a compound are very difficult to separate. • The properties of a compound are very different to the properties of the original elements.

48. You need to be able to describe techniques for separating mixtures.

49. You need to be able to describe techniques for separating mixtures. Filtration Simple distillation Fractional distillation Crystallisation Paper chromatography

50. Filtration Filtration depends upon the different size of particles in a mixture. The filtrate passes through the filter paper, the residue is left behind. The technique is used to separate an insoluble solid from a liquid, eg. sand and water.