Changes in Matter Physical vs. Chemical Changes

Physical Changes No new substance is formed No new substance is formed The particles are not changed The particles are not changed Usually just a change of state Usually just a change of state The change can be reversed The change can be reversed Example:Example: Dissolving Salt in Water Dissolving Salt in Water Dissolving Baking Soda in Water Dissolving Baking Soda in Water

Chemical Changes Always creates at least one new substance that has new properties Always creates at least one new substance that has new properties Can be difficult or impossible to reverse (can’t go back) Can be difficult or impossible to reverse (can’t go back) ExampleExample Adding vinegar to baking soda Adding vinegar to baking soda Burning paper Burning paper

Chemical Changes How do we know??

The seven observations that a chemical change has occurred: Heat or light is produced or absorbedHeat or light is produced or absorbed The starting material is used upThe starting material is used up A new colour appears or starting colour disappearsA new colour appears or starting colour disappears A material with new properties formsA material with new properties forms Gas bubbles form in a liquidGas bubbles form in a liquid Grains of solid precipitate form in a liquidGrains of solid precipitate form in a liquid The change is difficult to reverseThe change is difficult to reverse

Precipitate Precipitate A solid or solid phase separated from a solutionA solid or solid phase separated from a solution

Chemical or Physical Change? Why? 1. Sugar dissolves in water 2. A steak is well cooked 3. The filament of a light bulb glows when electricity runs through it 4. A piece of chalk is crushed 5. A seed grows into a shrub

Physical and Chemical Changes Vocabulary

Physical Vocabulary WordExample Grinding Rocks, Teeth, coffee, wheat Breaking Chalk, plate, bones, bottle Eroding Cliffs, beaches, soil Evaporating Water, alcohol Melting Ice, snow, wax Condensing Water from steam Drying Clothes, paint

More Physical Vocab WordExample Freezing Water, vegetables Cut Wood, paper, meat Stretch Elastic, rubber band Crumple/Crumble cookie, buildings SplitWood

Chemical Vocabulary WordExample Burning Wood, nylon, paper Rotting Food, wood, teeth Rusting Cars, metal, tools Reactions Vinegar, baking soda Digesting Food in stomach Respiration Gasses formed Photosynthesis Changes in plants