1 Kinetic Model Of Matter

2 The kinetic theory of matter states that all matter is made up of a large number of tiny atoms or molecules, which are in continuous, random motion.  These molecules are too small to be seen. However, the Brownian motion and the phenomenon of diffusion have demonstrated the existence of particles in continuous motion.

3 X-ray diffraction patterns of crystals and the striking photographs of crystals taken with electron microscopes provide further evidence of the particulate nature of matter.

4 Image : Image taken with a scanning tunneling microscopeImage : Image taken with a scanning tunneling microscope. This image is about 5 nanometers shows a copper surface where the copper atoms are contained within an enclosure quantum of 48 iron atoms. The circular barrier iron has a radius of 71.3 Angstroms (71.3 x10-10) meter. We see the electrons behave like waves. STM image (7 nm x 7 nm) of a single zigzag chain of cesium atoms (red) on a gallium-arsenside surface (blue)

5 Using a scanning tunneling microscope, the IBM logo was spelled out using 35 xenon atoms in April 1990. 

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7 Brownian Motion Brownian motion is named after the Scottish botanist Robert Brown who first observed it in He was using a microscope to study tiny grains of pollen suspended in water, when he noticed that the grains were constantly moving in a random manner.

8 Brownian Motion Brownian motion can also be seen when using a microscope to look at smoke particles floating in the air. The smoke particles are seen to move continuously and haphazardly. It was not until 1905 that Einstein (making his first major contribution to science) was able to explain how Brownian motion occurs.

9 Brownian Motion

10 Brownian Motion He suggested that the irregular or random motion of the smoke particles was the result of the smoke particles being hit by unseen air molecules which are moving at fast speed and randomly. Brownian motion, thereby, provides evidence of the movement of molecules.

11 Brownian Motion When the temperature increases, the motion of the smoke particles becomes more vigorous. Careful observations also show that the smaller the smoke particles, the more rapidly they move.

12 Brownian Motion We can now explain Brown's observation of the random motion of pollen grains in water: it is due to their bombardment by the water molecules. In other words, water molecules are in continuous and random motion.

13 Diffusion Diffusion is the random movement of liquid or gas particles to fill the available space and spread evenly, i.e to say the random motion of the gas particles causes the gases to mix until they are evenly distributed. For instance, if you pass by a trash can, you can smell the ugly scent of trash. This is because the gaseous molecules from the garbage diffused out of the can to the air which you breathed in.

14 Diffusion Diffusion of gases can be proved very easily. We can prove it by putting some bromine liquid in a cylinder and sealing it, then putting another inverted cylinder above it. When the bromine liquid evaporates, we remove the lid between the two cylinders, the brown bromine gas will diffuse upwards filling the available space.

15 Diffusion Diffusion rate depends on several factors, these are:Mass of the substance. The lighter the substance the faster it diffuses Temperature. The more kinetic energy the particles have, the faster they move and diffuse.

16 Diffusion Diffusion rate depends on several factors, these are:Presence of other substance. Diffusion is faster when it occurs in an area where there are fewer particles of other substances present. This is why diffusion is extremely fast in vacuums. This is because the diffusing particles have less other particles to stand in their way.

17 Diffusion Diffusion rate depends on several factors, these are:Intermolecular spaces. This is why gases diffuse faster than liquids and solids do not diffuse.

18 Three states of Matter

19 Solids Fixed shape and fixed volume Not compressibleDoes not flow easily

20 Solids (Kinetic Model)The molecules are arranged close together in a regular pattern. Solids cannot be compressed because the molecules are arranged close together and there is little space between them.

21 Solids (Kinetic Model)The molecules can only vibrate about their fixed positions, alternately attracting and repelling one another. There are balanced forces between the molecules which hold them in fixed positions.

22 Solids (Kinetic Model)The strong attractive forces prevent the molecules from leaving their positions while the repulsive forces which act when they are too close to each other prevent them from collapsing. This explains why a solid has a fixed shape and fixed volume.

23 Solids (Kinetic Model)When a solid is heated, the molecules gain energy and vibrate more vigorously. The separation between molecules increases slightly and the solid expands.

24 Liquids Fixed volume but no fixed shapeAssumes the shape of the container which it occupies Not easily compressible Flows easily

25 Liquids (Kinetic Model)The molecules are not arranged in a regular pattern and are slightly further apart than in solids. Liquids cannot be compressed as the molecules are close together and there is little space between them.

26 Liquids (Kinetic Model)The molecules also vibrate to and fro, alternately attracting and repelling one another with forces which can be just as strong as those in a solid. Though there are still forces between the molecules, they are not held in fixed positions. Because of this, the molecules move among one another throughout the liquid. That is why liquids flow and take the shape of their container.

27 Liquids (Kinetic Model)The attractive forces between the molecules make it difficult for the molecules to leave the liquid and thus liquids have a definite volume.  When a liquid is heated the molecules vibrate and move about vigorously. Thus the liquid expands slightly only to a very slight extent.

28 Gases No fixed shape and no fixed volumeAssumes the shape and volume of its container Highly compressible Flows easily

29 Gases (Kinetic Model) The molecules are far apartA gas can be compressed because the molecules are sparse and there is a lot of space between them. The molecules move randomly at high speed, colliding with one another and with the walls of the container.

30 Gases (Kinetic Model) The intermolecular forces act only at moments of collision. Otherwise, the molecules are so far apart that the forces of attraction become negligible. Therefore, a gas is free to fill a container completely.

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32 Recall: Properties of each state of matterSolids Liquids Gases Shape fixed shape no fixed shape Volume fixed volume no fixed volume Ability to be compressed incompressible compressible

33 States of Matter Based upon particle arrangementThe different states of matter are categorized by the arrangement and energy of the particles at normal temperatures and pressures. The state of matter can be altered by adding or removing energy and/or pressure which can affect the arrangement and energy of the particles. Based upon particle arrangement Based upon motion of particles Based upon distance between particles

34 Solids (Kinetic Model)Particles are held in position by strong attractive forces Particles in solids are tightly packed, vibrating about a fixed position. In other words, they do not move out of position or cannot move freely. Solids have a definite shape and a definite volume.

35 Liquids (Kinetic Model)Particles of liquids can slide over one another or slide past one another Still have relatively strong attractive forces between particles. Liquids have an indefinite shape and a definite volume.

36 Gases (Kinetic Model) Particles of gases are very far apart. They move freely and randomly at high speed. (intermolecular forces have been completely broken) Gases have an indefinite shape and an indefinite volume.

37 Kinetic Model Of Matter

38 Kinetic Model Of Matter

39 Ability to be compressedRemembered this? Solids Liquids Gases Shape fixed shape no fixed shape Volume fixed volume no fixed volume Ability to be compressed incompressible compressible Kinetic Model of Matter can be used to explain the properties for each state of matter

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41 A. The molecules of oxygen are widely spaced between one another.Q14. Which statement best explains why oxygen molecules do not have fixed shape and volume? A. The molecules of oxygen are widely spaced between one another. B. The molecules of oxygen have weak attractive force between one another. C. The molecules of oxygen move about freely and randomly in all directions. D. The molecules of oxygen have very low density. C A gas does not have fixed shape and volume due to the motion of its particles.

42 A. Helium particles shrink in size. Q15. What would happen to helium particles in a balloon when the balloon is compressed? A. Helium particles shrink in size. B. Helium particles arrange in a regular pattern. C. Helium particles have less space between each other. D. Helium particles vibrate only at their fixed positions. C The compressibility is affected by the spaces between the particles. For example, solids cannot be compressed easily because the particles in them are closely packed, so no space to be compressed.

43 A. The particles are closely packed in an orderly manner.Q16. Which of the following statements is not correct about the particles in an ice cube? A. The particles are closely packed in an orderly manner. B. The particles are able to vibrate only at their fixed positions. C. The particles have strong forces between each other. D. The particles are far apart from each other. D Answer D is only applied to gas. Ice cube is in solid state.

44 A. Water turns brownish when a tea bag is placed in it.Q17. Which of the following examples best illustrates the process of diffusion? A. Water turns brownish when a tea bag is placed in it. B. Jelly cubes are formed when the jelly solution is cooled. C. Water droplets form on the cold glass surface. D. Plastic toy melts when it is heated. A The ability of tea particles to move in water is the example of diffusion.

45 B. Electrical conductivity C. Melting point and boiling point Q18. Which of the following properties cannot be explained by the particulate model of matter? A. Compressibility B. Electrical conductivity C. Melting point and boiling point D. Expansion and contraction B The electrical conductivity is due to 'free electrons' of a substance (refers to unit Electricity).

46 Q19. Which of the following best explains why gases have lower densities than liquids and solids?A. The particle size of gases is generally smaller than those of liquids and solids. B. The number of particles in gases is less than that of an equal volume of solids and liquids due to the distance between the particles. C. The attractive force between the gas particles is extremely weak. As a result, the masses of the particles are negligible. D. Gases do not have fixed shapes. As a result, their densities are the lowest. B This question is the same as in question 2. It is to illustrate the spaces between the particles.

47 D. Water has a lower melting point than table salt.Q20. Which example gives the best evidence that a matter contains particles which are in constant motion? A. A metal spoon becomes hot immediately when it is placed in a cup of hot tea. B. The fragrance of a perfume can be detected all over the room when the cap of the perfume bottle is removed. C. A marble ball sinks to the bottom of a measuring cylinder which contains pure water. D. Water has a lower melting point than table salt. B This is another common example to illustrate the diffusion of a substance.

48 SQ1. Explain the following examples using the knowledge of the particulate model of matter.(a) A metal toy retains its shape after striking the surface of a hard floor. (b) Water drips down from the edge of a table after a glass is knocked down. (c) The fragrance of an air freshener in a washroom can be detected in the living room.

49 The particles are arranged in a closely packed pattern. SQ1. Explain the following examples using the knowledge of the particulate model of matter. (a) A metal toy retains its shape after striking the surface of a hard floor. The particles are arranged in a closely packed pattern. They are not able to move about. Therefore, the toy retains its shape. The particles in the metal cannot move freely but only vibrate about their fixed positions. They are held in position by very strong attractive forces. There are no very little empty spaces between the particles. Thus, the metal toy cannot be deformed easily and retains its shape.

50 Water molecules are able to move about freely within confined space. SQ1. Explain the following examples using the knowledge of the particulate model of matter. (b) Water drips down from the edge of a table after a glass is knocked down. Water molecules are able to move about freely within confined space. Therefore, water can flow and drips down from the edge of the table. Water molecules can roll and slide past one another. The attractive forces between the molecules are relatively strong. As a result, water can flow and drips down from the edge of the table.

51 SQ1. Explain the following examples using the knowledge of the particulate model of matter.(c) The fragrance of an air freshener in a washroom can be detected in the living room. The fragrant particles are able to move in all directions at high speed. Therefore, the particles can travel from the washroom to the living room. The fragrant particles have very little attraction between them. They move randomly at high speed. Therefore, the particles can diffuse from the washroom to the living room. (This mixing of different gases by random molecular motion with frequent collisions is called diffusion. Movement of a gas, liquid, or solid as a result of the random thermal motion of its particles (atoms or molecules).)

52 SQ2. Using the particulate model of matter, explain briefly the following observations.(a) Liquid mercury is more difficult to compress than helium gas. [2] (b) In an experiment, two gas jars containing different gases are arranged in the horizontal position as shown below. (i) Iodine gas fills both gas jars completely after one hour. Explain why it is so.[2] (ii) Use the particulate model of matter to explain this observation. [1]

53 SQ2. Using the particulate model of matter, explain briefly the following observations.(a) Liquid mercury is more difficult to compress than helium gas. [2] (b) In an experiment, two gas jars containing different gases are arranged in the horizontal position as shown below. (i) Iodine gas fills both gas jars completely after one hour. Explain why it is so.[2] (ii) Use the particulate model of matter to explain this observation. [1]

54 SQ3. In an experiment, a glass is inverted into a beaker of water as shown below. The water does not fill in the glass completely when the glass is inverted. (a) Suggest the possible objective for this experiment. (b)(i) Give one physical property of water in the beaker [1] (ii) Using the knowledge of the particulate model of matter, explain why water has the physical property in (b)(i). [2]

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56 Change in state Matter changes state when energy is added or removed.The motion and spacing of the particles determines the state of matter of the substance

57 Matter Solid Liquid Gas Melting Boiling Freezing CondensationDeposition Sublimation

58 Change in state

59 Melting is the process by which a solid changes to a liquidMelting is the process by which a solid changes to a liquid. Freezing is the reverse of melting Boiling or vaporization is the process by which a liquid changes to a gas or vapor. Condensation is the reverse of boiling or vaporization.

60 Sublimation is the process by which a solid changes to a gas or vapor directly without the formation of liquid. Iodine, mothballs

61 Heating Curve

62 Melting When a solid is heated, the particles absorb thermal energy.This increases the kinetic energy of the particles – the particles vibrate with greater amplitudes and faster and the average separation between them increases.

63 Melting At a certain temperature known as the melting point, the particles have enough energy to overcome the strong forces of attraction holding the particles together in the solid. The particles start to break away from one another and the solid becomes a liquid. At the liquid state, the particles start to roll and slide over one another.

64 Practice Think about how to explain boiling using kinetic particle theory or kinetic model of matter or particulate theory of matter.

65 Boiling Particles in a liquid are held by strong attractive forces.When a liquid is heated, the particles absorb thermal energy. The particles gain kinetic energy and move about more rapidly.

66 Boiling At a certain temperature known as the boiling point, the particles gain sufficient energy to overcome the attractive forces between the particles The liquid becomes gas and the particles become widely separated and move randomly at high speed.

67 Cooling Curve

68 25 C to an orderly arrangement at 10 C. Which statement is correct?Q1. A substance changes from the state in which its particles are arranged in a disorderly manner at 25 C to an orderly arrangement at 10 C. Which statement is correct? A. It is a liquid at 10 C. B. It is a solid at 25 C. C. It changes from liquid to solid when the temperature decreases from 25 C to 10 C. D. It melts when the temperature decreases from 25 C to 10 C. C. It changes from liquid to solid when the temperature decreases from 25 C to 10 C.

69 Q2. Which of the following does not involve the change of physical states of a matter?A. Freezing B. Condensation C. Evaporation D. Diffusion D. Diffusion

70 A. The attractive force between iodine particles is weakened. Q3. The diagram shows solid iodine crystals being heated until they sublime. Which change would not take place in the particles of iodine crystals when they sublime? A. The attractive force between iodine particles is weakened. B. The space between iodine particles becomes further apart. C. The motion of iodine particles becomes vigorous and random. D. The arrangement of iodine particles becomes closely packed together. D. The arrangement of iodine particles becomes closely packed together.

71 A. It does not occupy space. Q4. Which statement is true about table salt crystals when they change to liquid after melting? A. It does not occupy space. B. It does not take the shape of its container. C. It does not have a definite volume. D. It cannot be compressed easily. D. It cannot be compressed easily

72 (a) At which change(s), A to E, SQ1.The diagrams below show the arrangement of the particles in a substance in various states. (a) At which change(s), A to E, (i) would the particles have the least attractive force between them? (ii) would the particles move from far apart to quite closely packed? (iii) the particles break away from their fixed positions to move freely and randomly in all directions? (a) (i) C and E (ii) D (iii) E

73 SQ1.The diagrams below show the arrangement of the particles in a substance in various states.(b) Describe the changes in terms of the motion and distance of the particles that take place in A and D. A -The particles break away from their fixed positions. They can now roll and slide past over one another to move about within confined spaces. They are not closely packed anymore but slightly far apart from one another now. B - The particles slow down their speed. They cannot move freely in all directions but only roll and slide past over one another. The distance between them decreases so they become quite close to one another.

74 SQ2. The heating curve below illustrates the changes in the physical states of water at different temperatures.

75 (a) What is the physical state of water at room temperature (25 C)? (b)(i) At which temperature does the particles of water start to move away from their fixed positions? (ii) Describe the change of physical states of water at this temperature. (a) Liquid (b) (i) 0 °C (ii) It changes from solid to liquid.

76 (c) The particles are now able to move randomly at high speed from their confined spaces.(c) Describe the change that occurs at 100 °C in terms of the motion of the particles.

77 SQ5.(a) Explain why solid sugar crystals have fixed shape and volume. (b) What is diffusion? Explain why diffusion of substances is possible by using an appropriate example. (c) Explain how diffusion takes place in an open perfume bottle in terms of the particulate model of matter. After the qns, see the examiner report

78 Cannot move freely but vibrate about fixed positions. SQ5.(a) Explain why solid sugar crystals have fixed shape and volume. Cannot move freely but vibrate about fixed positions. Held in position by very strong attractive forces This explains why solids have fixed volumes and shapes After the qns, see the examiner report

79 SQ5 (b) What is diffusionSQ5 (b) What is diffusion? Explain why diffusion of substances is possible by using an appropriate example. Diffusion is the movement of a substance from a region of its high concentration to a region of its low concentration. After the qns, see the examiner report Paper 2 Page 7 Q3(e) ER Page 6 Page Page 86 Page 25 Q5 Page 88

80 SQ5 (b) What is diffusionSQ5 (b) What is diffusion? Explain why diffusion of substances is possible by using an appropriate example. Diffusion is the random movement of liquid or gas particles to fill the available space and spread evenly, i.e to say the random motion of the gas particles causes the gases to mix until they are evenly distributed. After the qns, see the examiner report

81 The gas jars are left undisturbed after the lid is removed. SQ5 (b) What is diffusion? Explain why diffusion of substances is possible by using an appropriate example. Diffusion of a substance can be demonstrated by using brown bromine gas. A gas jar containing air is inverted over another gas jar with bromine gas, separated by a lid initially as shown. The gas jars are left undisturbed after the lid is removed. After a period of time, both jars contain brown bromine gas. This shows that diffusion of bromine gas has taken place. Show the Bromine video

82 (c) Explain how diffusion takes place in an open perfume bottle in terms of the particulate model of matter. When a perfume bottle is not closed, the perfume particles changes into gas. The concentration of the perfume particles is at high concentration above the perfume bottle, so they diffuse freely at high speed in all directions.  faster moving/more energetic molecules escape from liquid/diffusion/ random movement of molecules/ molecules get mixed up with molecules in the air/ molecules of the perfume collide with molecules in the air

83 faster moving/more energetic molecules escape from liquid/diffusion/ (c) Explain how diffusion takes place in an open perfume bottle in terms of the particulate model of matter. faster moving/more energetic molecules escape from liquid/diffusion/ random movement of molecules/ molecules get mixed up with molecules in the air/ molecules of the perfume collide with molecules in the air faster moving/more energetic molecules escape from liquid/diffusion/ random movement of molecules/ molecules get mixed up with molecules in the air/ molecules of the perfume collide with molecules in the air

84 SQ4. Two liquids, M and N, are poured into the same measuring cylinders as shown below.(a) Using the knowledge of the particulate model of matter, explain why the final volume of the mixture is less than 60 cm3. (b) If the size of the particles of M is bigger than that of N, draw the arrangement of particles in the mixtures in the box provided below. [Use O as the particles of M and • as the particles of N]

85 SQ4. Two liquids, M and N, are poured into the same measuring cylinders as shown below.(a) Using the knowledge of the particulate model of matter, explain why the final volume of the mixture is less than 60 cm3. There are spaces between the particles. The smaller particles will fill in the spaces between the bigger particles. Therefore, the volume is less than 60 cm3.

86 SQ4. (b) If the size of the particles of M is bigger than that of N, draw the arrangement of particles in the mixtures in the box provided below. [Use O as the particles of M and • as the particles of N]

87 Practice Think about how to explain freezing using kinetic particle theory or kinetic model of matter or particulate theory of matter.