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States of Matter

States of Matter. Kinetic Theory. An everyday activity such as eating lunch may include some states of matter. Q : Can you identify the states of matter present (and absent) in the photo?. Kinetic Theory. kinetic theory: an explanation of how particles in matter behave.

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States of Matter

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  1. States of Matter Kinetic Theory

  2. An everyday activity such as eating lunch may include some states of matter. Q: Can you identify the states of matter present (and absent) in the photo?

  3. Kinetic Theory kinetic theory: an explanation of how particles in matter behave

  4. Three assumptions of the kinetic theory: 1. All matter is composed of small particles (atoms, molecules, and ions). 2. These particles are in constant, random motion. 3. These particles are colliding with each other and the walls of their “container”.

  5. Thermal Energy Thermal energy: the total energy of a material’s particles; includes… 1. kinetic energy—vibrations and movement within and between the particles AND 2. potential energy—resulting from forces that act within or between particles

  6. Atoms in solids, for example, are held tightly in place by the attraction between the particles. This attraction between the particles gives solids a definite shape and volume. However, the thermal energy in the particles causes them to vibrate in place.

  7. Temperature: Average Kinetic Energy temperature: the average kinetic energy of particles in the substance = how fast the particles are moving So, which will move more slowly? molecules of frozen water at 0°C or molecules of water at 100°C? A: molecules of frozen water

  8. So, water molecules at 0°C also have a lower average kinetic energy than the molecules at 100°C. Molecules will have kinetic energy at all temperatures, including absolute zero.

  9. Solid State 1. closely packed particles 2. definite volume & definite shape… important for its chemical and physical properties

  10. Liquid State: How are Liquids Formed? • What happens to a solid when thermal energy or heat is added to it? • The particles on the surface of the solid vibrate faster. • 2. They collide with and transfer energy to other particles. • 3. Soon they have enough kinetic energy to overcome the attractive forces.

  11. 4. The particles gain enough kinetic energy to slip out of their ordered arrangement, and then the solid melts. 5. This is the melting point: the temperature at which a solid begins to liquefy

  12. Liquid Flow Do particles in a liquid have more or less kinetic energy than particles in a solid? More… so they are moving faster

  13. This extra kinetic energy allows particles to partially overcome the attractions to other particles.

  14. Liquid Flow Thus, the particles can slide past each other, allowing liquids to flow and take the shape of their container.

  15. However, the particles in a liquid have not completely overcome the attractive forces between them This causes the particles to cling together, giving liquids a definite volume.

  16. Liquids • Can flow (slide past each other) • Have no definite shape ( they take the shape of their container) • Have a definite volume

  17. Liquid To Gas State How does a liquid become a gas? The particles in a liquid are constantly moving…

  18. Some particles are moving faster and have more kinetic energy than others. The particles that are moving fast enough can escape the attractive forces of other particles and enter the gas state.

  19. This process is called vaporization: going from liquid to gas phase Vaporization can occur in two ways—evaporation and boiling. Evaporation: vaporization that occurs at the surface of a liquid and can occur at temperatures below the liquid’s boiling point

  20. boiling point: the temperature at which the pressure of the vapor in the liquid is equal to the external pressure acting on the surface of the liquid

  21. Heat of vaporization: the amount of energy required for the liquid at its boiling point to become a gas

  22. Gas State • Gas particles: • have enough kinetic energy to overcome the attractions between them • 2. do not have a fixed volume or shape • 3. can spread far apart or contract to fill the container that they are in

  23. Gases Fill Their Container diffusion: the spreading of particles throughout a given volume until they are uniformly distributed

  24. See animations: Movement of Particles in Different States of Matter

  25. Heating Curve of a Liquid This type of graph is called a heating curve because it shows the temperature change of water as thermal energy, or heat, is added. Notice the two areas on the graph where the temperature does not change. At 0°C, ice is melting.

  26. Heating Curve of a Liquid The temperature remains constant during melting. After the attractive forces are overcome, particles move more freely and their average kinetic energy, or temperature, increases.

  27. At 100°C, water is boiling or vaporizing and the temperature remains constant again.

  28. Plasma State Scientists estimate that most of the matter in the universe is plasma (most similar to gases). Plasma: matter consisting of positively and negatively charged particles (its overall charge is neutral because equal numbers of both charges are present… high energy collisions strip off electrons)

  29. Plasma State All of the observed stars including the Sun consist of plasma. Plasma also is found in lightning bolts, neon and fluorescent tubes, and auroras.

  30. Amorphous Solids 1. do not have a definite temperature at which they change from solid to liquid 2. merely soften and gradually turn into a liquid over a temperature range 3. lack the highly ordered structure found in crystals 4. from the Greek word for “without form.”

  31. Amorphous Solids example: obsidian—a volcanic glass formed when liquid matter changes to solid matter too quickly for an orderly structure to form

  32. Liquid Crystals 1. start to flow during the melting phase similar to a liquid, but they do not lose their ordered arrangement completely, as most substances do 2. placed in classes depending upon the type of order they maintain when they liquefy 3. highly responsive to temperature changes and electric fields

  33. Liquid Crystals Scientists use these unique properties of liquid crystals to make liquid crystal displays (LCD) in the displays of watches, clocks, and calculators.

  34. Question 1 What are the three assumptions of the kinetic theory?

  35. Answer The three assumptions are that 1. all matter is composed of small particles, 2. these particles are in constant random motion, and 3. these particles are colliding with each other and with the walls of their containers.

  36. Question 2 What is the difference between thermal energy and temperature?

  37. Answer Thermal energy is the total amount of kinetic and potential energy of a materials’ particles; temperature is a measure of the average kinetic energy of a material’s particles.

  38. Question 3 The temperature at which a solid begins to liquefy is called its __________. • boiling point • heat of fusion • heat of vaporization • melting point

  39. Answer The answer is D. The heat of fusion is the amount of energy required; melting point is a temperature.

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