1. Unit 2: Heat Chapter 5 Section 5.3: Changes of State (Slide Show #2)

2. Changes of State Substances can change between these three states. Do you recognize these changes of state? Substances can change between these three states. Do you recognize these changes of state? – Melting Ice (solid) melts to water (liquid) Ice (solid) melts to water (liquid) – Evaporation Water (liquid) evaporates into steam (gas) Water (liquid) evaporates into steam (gas) – Condensation Steam (gas) condenses to water (liquid) Steam (gas) condenses to water (liquid) – Freezing Water (liquid) freezes to ice (solid) Water (liquid) freezes to ice (solid) – Sublimation Steam to ice OR ice to steam (skips the liquid phase) Steam to ice OR ice to steam (skips the liquid phase)

3. Changes of State (PTM) Here are the basics of the changes of state according to the PTM: Here are the basics of the changes of state according to the PTM: – When the particles of a solid gain enough energy (from heat) to move freely, the substance becomes a liquid (loses its shape). – With even more energy, the particles may begin to break free from the surface of the liquid (attractions become weak) and the substance becomes a gas. Can you guess what happens when the particles lose energy (cooled)? Can you guess what happens when the particles lose energy (cooled)?

4. Changes of State Melting Melting: changing from a solid to a liquid. – According to the particle theory of matter: Temperature warms to above 0 o C. Particles gain energy and hence have more movement. –Loses its shape (particles are free to move) Attractions, however, are still strong. –Keeps its volume Substance is now a liquid since it has indefinite shape but definite volume. – Animation of ice melting Animation of ice melting

5. Changes of State Evaporation Evaporation: liquid to a gas – According to the particle theory of matter: Temperature warms to above 100 o C. Particles gain a lot of energy and move randomly in all directions. –Still has no shape Attractions become weak and the particles break free from the surface of the liquid. –Loses its volume Substance is now a gas since it has indefinite shape and indefinite volume.

6. Changes of State Condensation Condensation: gas to a liquid. – According to the particle theory of matter: Temperature cools to below 100 o C. Gas particles lose energy and do not have as much movement, but are still free to move around. –Still has no shape Particles again become attracted to each other. –Regains its volume Substance is now a liquid since it has indefinite shape but definite volume. – Which process is the opposite of condensation?

7. Changes of State Freezing Freezing: liquid to a solid – According to the particle theory of matter: Temperature cools to below 0 o C. Particles lose energy and have very little movement. –Regains its shape The attractions are still strong. –Retains its volume Substance is now a solid since it has a definite shape and definite volume.

8. Changes of State Sublimation Sublimation: solid to a gas. – According to the particle theory of matter: Temperature warms from below 0 o C to above 100 o C very quickly. Particles gain a lot of energy and move randomly in all directions. –Loses its shape Attractions become very weak. –Loses its volume Substance is now a gas because…

9. Changes of State Deposition (crystallization) Deposition: gas to a solid – According to the particle theory of matter: Temperature… Energy… Movement… –This means… Attractions… –This means…

11. States of Matter Check out the following website: Check out the following website: – http://www.chem4kids.com/files/matter_intro.h tml http://www.chem4kids.com/files/matter_intro.h tml http://www.chem4kids.com/files/matter_intro.h tml