1. Observing Chemical Change
Chapter 6 Section 1:
Observing Chemical Change

2. Property and changes of matter
Matter can be described in terms of physical and chemical changes

3. A physical property is a characteristic of a substance that can be observed without changing the substance into another substance

4. Melting pt, boiling pt, color, hardness, texture, luster, ductility, malleability, conduction of heat and electricity

5. A chemical property is a characteristic of a substance that describes its ability to change into another substance(s).

6. Reactivity to Oxygen, burning/ flammability, tarnishing, and rusting
See figure 1, page 185

7. A physical change is any change that alters the form or appearance of a substance but it does not make the substance change into another substance

8. Bending, crushing, breaking, cutting

9. A chemical change is when the substance itself changes into another substance. This is called a chemical reaction.

10. Burning
Chemical changes occur when bonds break and new bonds form

11. Evidence for Chemical Reactions
Involve the formation of a new substance and changes in energy.
Figure 4, page 188

12. Changes in properties result when new substances form

13. A solid that forms from a solution during a chemical reaction is called a precipitate

14. Color change

15. A gas might be produced

16. Changes in energy
Matter can either absorb or release energy in the form of heat, light, electricity

17. Occurs during chemical reactions

18. A change in temperature indicates absorption or release of energy

19. Endothermic: energy is absorbed, temperature does not always result in a decrease. Energy must continuously be added to have endothermic reactions (Bonds are being broken, energy is needed)( Takes energy from surroundings)
Ammonium thiocyanate is mixed with barium hydroxide.
A drop of water is placed on a block of wood.
The bottom of the beaker becomes cold enough to freeze the water and stick to the wood.

20. Exothermic: energy is released as heat so the temperature increases
(Bonds are being formed, have more energy than needed)
(Heat given to surroundings)