1. Chemical Properties and Changes

2. Property = a characteristic that gives a substance identity Properties of Vinegar: - clear liquid - density is 1.08 g/mL -strong odor - reacts with baking soda - acidic

3. Composition = the ingredients or make-up of a substance, often represented by a chemical formula Water is composed of Hydrogen and Oxygen Emeralds are composed of Al, Be, Si and O Diamonds are composed of Carbon only

4. Physical Property can be observed without changing composition “depends on the matter itself” Chemical Property Only can be observed when composition changes. “depends on its reaction with other matter” Methanol / Water

5. Important Physical Properties: Color Opacity Density Magnetism Conductivity –(ability to conduct heat or electricity) Solubility –(ability to form a solution in water or other solvent) Crystal Form –(grain size, geometric shape of crystal)

6. There is only one chemical property: …whether something will react with (have a chemical reaction with) another substance. REACTIVITY

7. What is a Chemical Reaction? Chemical Reaction: …a rearrangement of the atoms in a substance to produce new substances

8. All chemical reactions can be written as: chemical equations: for example: Methanol + Oxygen  Carbon Dioxide + Water or: CH 3 OH + O 2  CO 2 + 2H 2 O REACTANTS PRODUCTS REACTANTS PRODUCTS

9. …that describes whether something will have a chemical reaction (chemical change) with another substance. So, REACTIVITY is a chemical property

10. Examples of Reactivity: Reaction with…____ Flammability (reaction with O 2 ) pH (reaction with water…whether something is an ‘acid’ or a ‘base’) Solder / Mg

11. Turn litmus paper red React with bases to form salts Taste Sour Turn litmus paper blue React with acids to form salts Taste Bitter ACIDSBASES pH: An important chemical property. pH = a measure of how acidic or basic a substance is.

12. pH = a measure of how acidic or basic a substance is ACIDSBASES

13. Which are Physical Properties? Which are Chemical Properties? Hardness…………………… Color………………………. Reactivity with HCl………. Magnetism………………... Density……………………. pH…………………………. Flammability……………… Boiling Point……………… Corrosiveness……………… Melting Point……………… Physical Chemical Physical Chemical Physical Chemical Physical

14. Physical Change Chemical Change = “chemical reaction” New substances are formed. Chemical Formulae are new or changed, Examples; - Crushing into Powder - All Phase Changes Examples; - Wood Burning (Combustion) -Iron Rusting (Oxidation) No new substances are formed. No change in chemical formula

15. 5 Signs of a Chemical Reaction: Formation of a gas Formation of a solid Unpredictable Color Change Radiant Energy (Light) Thermal Energy (Heat) Q: How can we tell if a chemical change has occurred? A: Look for evidence…

16. Ice Melting: Chemical or Physical Change? Composition does not change; it is still water (H 2 O). No new substances are formed, so no chemical change. PHASE CHANGE = PHYSICAL CHANGE

17. Phase Changes and Kinetic Theory

18. When a candle melts, some of the wax turns to a liquid and runs down the side. Is this a chemical change or a physical change? Why? Does the candle become a new substance? It was wax; it is still wax; liquid wax is still wax Physical Change

19. Is lighting a match a chemical change or a physical change? Why? Is a new substance produced? Does a color change occur? Is heat and light given off? Is a gas produced? Chemical Change Enough!