Physical and Chemical Changes

1. Physical and Chemical Changes

2. 2 different ways matter can change: • Physical change • a change in the form/state or appearance of a substance without making a new substance

3. Physical Changes cont’d: Clues that a physical change has occurred: • physical and chemical properties remain the same • change is easy to reverse

4. Chemical change • a change that makes a NEW substance that almost always appears different from the original substance • physical and chemical properties change

5. Chemical changes cont’d: 5 clues that a chemical change has occurred: • a new colour appears • heat or light is given off (energy) • bubbles of gas are formed • a solid material (precipitate) forms in a liquid • the change is difficult to reverse

6. DEMO TIME: • Watch each of the following demonstrations and place it in the correct chart, as either a physical or chemical change. • Complete the chart by answering the “How do you know?” column

7. Chemical Changes are often referred to as ChemicalReactions. Chemical Equation • a shorthand way of describing a chemical reaction using chemical symbols Word Equation • uses words rather than chemical symbols

8. Chemical and Word Equations: REACTANTSPRODUCTS special conditions • materials that start a reaction • materials made by the reaction

9. Example of a Word Equation: Copper + Oxygen Copper Oxide Read as: “Copper reacts with oxygen to produce copper oxide”

10. + means “reacts with” means “to produce” means a gas means a precipitate

11. Home Fun : 1) Complete the “Word Equations Homework” and the “Physical and Chemical Changes” chart.