Physical changes alter the physical properties of a substance but do not change its chemical composition. Chemical changes produce new substances through chemical reactions. Some signs that a chemical change has occurred include a color change, gas formation, changes in temperature or light emission, precipitation of a solid, or production of a gas. Common examples of physical changes are melting, freezing, and cutting, while chemical changes include burning, digestion, and rusting.

1. Chemical Properties & Physical and Chemical Changes

2. Physical changes are those changes that do not result in the production of a new substance. If you melt a block of ice, you still have H 2 O at the end of the change.

3. If you break a bottle, you still have glass. Painting your nails will not stop them from being fingernails. Some common examples of physical changes are: melting, freezing, condensing, breaking, crushing, cutting, and bending.

4. Some, but not all physical changes can be reversed. You could refreeze the water into ice, but you cannot put your hair back together if you don’t like your haircut!

5. Special types of physical changes where any object changes state, such as when water freezes or evaporates, are sometimes called change of state operations .

6. CHEMICAL PROPERTIES Chemical properties can ONLY be observed AS the substances are changing into different substances.

7. Chemical changes , or chemical reactions, are changes that result in the production of another substance.

8. FLAMMABILITY: A material’s ability to BURN in the presence of OXYGEN

9. REACTIVITY: How readily (easily) a substance combines chemically with other substances.

10. Which has higher reactivity? A 14 karat gold ring or a cheap metal ring from the vending machine at the grocery store? What is your evidence?

11. When you burn a log in a fireplace, you are carrying out a chemical reaction that releases carbon. When you light your Bunsen burner in lab, you are carrying out a chemical reaction that produces water and carbon dioxide.

12. Common examples of chemical changes that you may be somewhat familiar with are; digestion, respiration, photosynthesis, burning, and decomposition.

13. Physical or Chemical Change? Painting Wood PHYSICAL

14. Physical or Chemical Change? Burning Paper CHEMICAL

15. Physical or Chemical Change? Digestion of food CHEMICAL

16. Physical or Chemical Change? Sugar dissolving in water PHYSICAL

17. Physical or Chemical Change? Iron turning red when heated PHYSICAL

18. Physical or Chemical Change? Evaporation PHYSICAL

19. Physical or Chemical Change? A pond freezing in winter PHYSICAL

20. Physical or Chemical Change? Melting ice PHYSICAL

21. Physical or Chemical Change? Cutting wire PHYSICAL

22. Physical or Chemical Change? Painting fingernails PHYSICAL

23. Physical or Chemical Change? Cutting fabric PHYSICAL

24. Physical or Chemical Change? Baking muffins CHEMICAL

25. Physical or Chemical Change? Shattering glass PHYSICAL

26. Physical or Chemical Change? Decomposition of old leaves CHEMICAL

27. Physical or Chemical Change? Wrinkling a shirt PHYSICAL

28. Physical or Chemical Change? An old nail rusting CHEMICAL

29. Signs for chemical changes Color change Gas formation (fizzing/bubbles) Change in light and temperature Precipitate (solid formation)

30. Concept Review pg. 5 Substance composed by one kind of atoms, and can not be decomposed in simpler substances by physical or chemical means: PURE SUBSTANCE (elements and compounds) Smallest particle that conserves the properties of an element ATOM

31. Pure substance formed by two or more different elements that are chemically combined in fixed proportions: COMPOUND Shortened way to represent an element's name: CHEMICAL SYMBOL A symbolic way for representing the composition of a substance: CHEMICAL FORMULA