1. Freezing/Melting and Boiling Points

2. Spacing of Molecules in a Solid, Liquid, & Gas Use this link http://www.chem.purdue.edu/gchelp/liquids/cha racter.html http://www.chem.purdue.edu/gchelp/liquids/cha racter.html

3. Freezing/Melting Point What is freezing point? It is the temperature at which a liquid becomes a solid

4. Freezing/Melting Point What is melting point? It is the temperature at which a solid becomes a liquid

5. Freezing/Melting Point What is the unit of measurement that scientists use for temperature? Celsius What is the temperature at which a WATER (liquid) becomes a solid (ice or snow)?

6. Freezing/Melting Point What is the temperature at which a WATER (liquid) becomes a solid (ice or snow)? Use the thermometer to measure the temperature

7. Freezing/Melting Point What is the temperature at which a WATER (liquid) becomes a solid (ice or snow)? You should have gotten a temperature right around 0 o degrees Celsius If you did not get 0 o - your thermometer may not be very accurate

8. Freezing/Melting Point If the temperature warms up 1 degree above 0 o Celsius – what happens? The ice or snow will melt Or change from a solid to a liquid

9. Freezing Point On your handout, use a marker to color in the temperature at which water freezes or becomes a solid (ice or snow) on the “Freezing Point” thermometer Water freezes at ____ degrees Celsius Water is a liquid that changes to a solid when it freezes.

10. Boiling Point What is a boiling point? It is the temperature at which a liquid becomes a gas. Gas

11. Boiling Point What is the boiling point of water? Does water continue to get hotter the longer you let it boil? Let’s try it & see

12. Boiling Point At what temperature did the water boil? 100 o Celsius Did the water continue to get hotter the longer you let it boil? No Once the water boils, it will not get any hotter – it will continue to boil until it all the liquid changes into a gas

13. Boiling Point On your handout, use a marker to color in the temperature at which water (a liquid) boils or becomes a gas on the “Boiling Point” thermometer Water boils at ____ degrees Celsius Water is a liquid that changes to a gas when it boils.

14. Heating Chocolate What happens to chocolate when we heat it? Is the chocolate chip a solid or liquid? It’s a solid Place one chip on your spoon and hold it over the candle for about 45 seconds Use your tooth pick to poke it

15. Heating Chocolate What happens to chocolate when we heat it? Is the chocolate chip a solid or liquid AFTER heating? It’s turning into a liquid Did it boil or change into a gas? NO

16. 5.7D - Science concepts (Objective 3 - Physical Sciences). The student knows that matter has physical properties. The student is expected to: observe and measure characteristic properties of substances that remain constant such as boiling points and melting points. Let’s try some practice TAKS questions

17. Water boils at 100 o C

19. Does it change into a gas? Yep!