Kinetic Theory of Matter. Matter & Energy

Transcription

1 Kinetic Theory of Matter Matter & Energy 1

2 Kinetic Theory of Matter All matter is made up of atoms and molecules that act as tiny particles. 2

3 Kinetic Theory of Matter These tiny particles are always in motion. 3

4 Kinetic Theory of Matter State of matter depends on its molecular motion as measured by temperature 4

5 Kinetic Theory of Matter Increase temperature = increased motion of particles Decrease temperature = decreased motion of particles 5

6 Kinetic Theory of Matter At the same temperature, heavier particles move slower than lighter particles. 6

7 Temperature A measure of the average kinetic energy (K.E.) in a sample. 7

8 Absolute Zero Temperature at which all molecular (particle) motion stops. 0 Kelvin -273 C -459 F 8

9 Intermolecular Forces (IF s) Force of attraction between molecules/particles. Intermolecular Force Become stronger as molecules get closer together; therefore IF s are strongest in solids. 9

10 States of Matter The Four States of Matter Solid Liquid Gas Plasma 10

11 States of Matter The Four States of Matter The Classification and Properties of Matter Depend Upon Microscopic Structure 11

12 Basis of Classification of the Four Types particle arrangement energy of particles distance between particles 12

13 Solids Particles are held by intermolecular forces (bonds between molecules) Particles of solids are tightly packed, vibrating about a fixed position. In other words, they do not move out of position. Solids have a definite shape and a definite volume. 13

14 Solids Particle Movement Examples 14

15 Liquids Particles of liquids are tightly packed, but are far enough apart to slide over one another. (intermolecular forces have weakened) Liquids have an indefinite shape and a definite volume. So, liquids take the shape of whatever container they are in but they cannot be squeezed into a smaller volume 15

16 Liquids Chumbler - Properties of Matter 16

17 Liquids Particle Movement Examples 17

18 Gases Particles of gases are very far apart and move freely. Intermolecular forces have been completely broken 18

19 Gases Gases have an indefinite shape and an indefinite volume. Volume CAN change! b/c particles are not close together, they can be squeezed into a smaller space ex. Pumping up a bicycle tire 19

20 Gases Particle Movement Examples 20

21 Plasma A plasma is a gaslike mixture of + and charged particles A plasma is a very good conductor of electricity ex. Fluorescent lights, stars Plasma, like gases have an indefinite shape and an indefinite volume. Most common state of matter in the universe. 21

22 Plasma Particles The negatively charged electrons (yellow) are freely streaming through the positively charged ions (blue). 22

23 Phase Changes Melting Freezing (solidification) Boiling(vaporization) Condensing Evaporation 24

24 Phase ChangeDiagram Chumbler - Properties of Matter 25

25 Melting & Freezing Change from solid to liquid, melting. Change from liquid to solid, freezing. Same temp 0 degrees C. Melting, particles are gaining energy Freezing, particles are losing energy. 26

26 During the phase change, the temp. remains constant. (flat/horizontal region on a phase diagram.) 27

27 After all the sample has changed phase, the temp. will change. During the phase change, potential energy (P.E.) is changing, but K.E. is constant. 28

28 Boiling And Condensation Boiling change from liquid to gas. Condensation change from gas to liquid. Occurs at the Same temp. 29

29 Boiling & Condensation Boiling, particles are gaining energy. Liquid to a gas. Condensing, the particles are losing energy. Gas to a liquid. 30

30 Boiling & Condensation During the phase change, the temp. remains constant. Flat/horizontal region on a phase diagram. 31

31 Evaporation Liquid to gas. Not at the boiling point temperature. Some particles gain enough K.E. to overcome the IF s and become a gas. Remember, temperature is a measure of the average K.E.! 32

32 Evaporation Chumbler - Properties of Matter 33

33 Evaporation vs Boiling Chumbler - Properties of Matter 34

34 Understanding Heat Transfer, Conduction, Convection and Radiation

35 Heat Transfer Heat always moves from a warmer place to a cooler place. Hot objects in a cooler room will cool to room temperature. Cold objects in a warmer room will heat up to room temperature.

36 Heat Transfer Methods Heat transfers in three ways: Conduction Convection Radiation

37 Conduction When you heat a metal strip at one end, the heat travels to the other end. As you heat the metal, the particles vibrate, these vibrations make the adjacent particles vibrate, and so on and so on, the vibrations are passed along the metal and so is the heat. We call this? Conduction

38 Metals are different The outer e lectrons of metal atoms drift, and are free to move. When the metal is heated, this sea of electrons gain k inetic energy and transfer it throughout the metal. Insulators, such as w ood and p, lastic do not have this sea of electrons which is why they do not conduct heat as well as metals.

39 Why does metal feel colder than wood, if they are both at the same temperature? Metal is a conductor, wood is an insulator. Metal conducts the heat away from your hands. Wood does not conduct the heat away from your hands as well as the metal, so the wood feels warmer than the metal.

40 Convection What happens to the particles in a liquid or a gas when you heat them? The particles spread out and become less dense. This affects fluid movement. What A liquid is a or fluid? gas.

41 Fluid movement Cooler, more d, ense fluids sink through w, armer less dense fluids. In effect, warmer liquids and gases r ise up. Cooler liquids and gases s. ink

42 Water movement Cools at the surface Convection current Cooler water sinks Hot water rises

43 Why is it windy at the seaside?

44 Cold air sinks Where is the freezer compartment put in a fridge? It is put at the top, because cool air sinks, so it cools the food on the way down. Freezer compartment It is warmer at the bottom, so this warmer air rises and a convection current is set up.

45 The third method of heat transfer How does heat energy get from the Sun to the Earth? There are no particles between the Sun and the Earth so it CANNOT travel by conduction or by convection.? RADIATION

46 Radiation Radiation travels in straight lines True/False Radiation can travel through a vacuum True/False Radiation requires particles to travel True/False Radiation travels at the speed of light True/False

47 Thermal Expansion Thermal expansion- matter expands as it gets hotter and contracts when it cools 48

48 Experiment 1: Expansion of solids metal ring metal ball 1. Before heating, the metal ball is able to go through the ring. Predict what happen when we heat the metal ball to high temperature! Why? Ans: 49

49 Heat Transfer Methods Heat transfers in three ways: Conduction Convection Radiation

50 Thermal Expansion After heating, the metal ball expands and is unable to go through the ring. Chumbler - Properties of Matter 51

51 Experiment 1: Expansion of solids Before heating, the metal ball is able to go through the ring. Predict what happen when we heat the metal ring to high temperature! Why? 52

52 Problems caused by expansion Solution: Introduce expansion gap Why? 53

53 Thermal Expansion Ex. Expansion joints on bridges, gaps in sidewalk 54

54 Thermal Expansion Exceptionwater actually expands when it freezes! 55