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2. Physical Properties  Characteristics observed that don’t change identity  Physical properties help identify substances

3. Measuring Physical Properties  Melting point- substance changes from a solid to a liquid.  Boiling point- substance changes from a liquid to a gas  Others: strength, hardness, magnetism, ability to conduct electricity, density

4. Chemical Properties  Describes how a substance changes into a new substance  Can happen by combining with other elements or breaking down  Generally not easy to observe

5. Examples of Chemical Properties  Flammability –the ability to burn  Reactivity-the capability of a substance to combine with another substance  Ex. Iron combining with oxygen

7. Physical Changes  Affects physical properties of a substance without changing the identity of a substance.  Ex. melting, cutting, crushing, dissolving

8. Chemical Change  When one or more substances are changed into entirely new substances that have different properties  Ex. a battery dying, leaves changing colors, rust  Chemical changes can not be reversed by physical changes!  Ex. Unbaking food

9. Clues for chemical changes  Odor  Change in color  Fizzing or foaming  Production of sound, light, or heat  Production of a solid (called a precipitate)

10. Which is which?  Identify which changes are physical and which are chemical