1. CHANGES OF MATTER

2. OBJECTIVES Explain physical change, and give examples of physical changes Explain chemical changes and give examples of chemical changes Compare and contrast physical and chemical changes Describe how to detect whether a chemical change has occurred

3. PHYSICAL CHANGES  A physical change is anything that affects one or more physical properties of a substance without changing its identity  Examples:  Dissolving sugar  Melting Ice  Sanding a piece of wood  Cutting hair  Can you name some more?

4. PHYSICAL CHANGES CONT.  Physical changes do NOT change the identity of a substance  During physical changes ________ is absorbed or released  After a physical change, a substance may look different but, the atoms that make it up are the same.  Any change in state, is a physical change  What are some changes in state?  Mixtures can be physically separated because they are not _________________ heat Boiling, melting, evaporating, & freezing chemically bonded

5. HOW CAN WE SEPARATE MIXTURES? 1.Use a centrifuge 2.Distillation which uses boiling and evaporation to separation components 3.Magnetism  Name some other examples.

6. CHEMICAL CHANGES  A chemical change occurs when 1 or more substances are completely changed into new substances with different properties  Examples:  Spoiling milk  Oxidizing metal (rusting)  Baking cupcakes  Can you name some more?

7. CHEMICAL CHANGES CONT.  Chemical changes happen everywhere!  Chemical changes form new substances with new properties  Chemical changes can be detected  Chemical changes often cause color changes, fizzing or foaming, or the production of sound, heat, light, or odor  Chemical changes can NOT be reversed by _____________ changes  They are difficult to undo physical

8. COMPOUNDS & CHEMICAL CHANGES  Some compounds can be broken down into elements through chemical changes.  Using methods such as heating and passing an electric current through it  Other compounds undergo chemical changes to form simpler compounds.  For example, carbonic acid in pop breaks down into carbon dioxide and water

9. PHYSICAL CHANGE VS. CHEMICAL CHANGE Physical ChangeChemical Change The substances present at the beginning are not present at the end The composition of matter ALWAYS changes New substances are made It can not be undone Occurs at the molecular level For example: rusting a nail, cooking an egg, burning wood The substances at the beginning are the same before and after the change The composition of matter does NOT change It can be undone For example: melting an ice cube Includes words like tearing, cutting, carving, melting, boiling, freezing, breaking