Unit 8 Lesson 3 What Are Some Chemical Changes? Copyright © Houghton Mifflin Harcourt Publishing Company

Chemical Properties What happened to the cup? Unit 8 Lesson 3 What Are Some Chemical Changes? Chemical Properties What happened to the cup? Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 8 Lesson 3 What Are Some Chemical Changes? Chemical Properties A chemical property is a property that describes how a substance interacts with other substances. Substances can be identified and grouped based on their chemical properties. The ability to rust or not rust is a chemical property. So is the ability to burn or not burn. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 8 Lesson 3 What Are Some Chemical Changes? Chemical Properties Chemical properties can help to predict how substances will change in different conditions. When heated in the oven the ingredients of pizza dough interact to form a pizza. If the dough is put in the refrigerator, pizza will not form. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 8 Lesson 3 What Are Some Chemical Changes? A chemical change takes place when a substance changes into an entirely new substance. Rust, rotting leaves, and rubber breaking down over time are all chemical changes. Copyright © Houghton Mifflin Harcourt Publishing Company

Chemical Changes Rust is the reddish brown stuff on a car where paint has peeled off, exposing the metal frame.

Mass

Unit 8 Lesson 3 What Are Some Chemical Changes? Iron and oxygen combined chemically to make a new substance: rust. No matter is created. The same amount of matter, or mass, is present before and after a chemical change. The mass is conserved during a chemical change. Copyright © Houghton Mifflin Harcourt Publishing Company

Chemical Changes

Chemical Changes Unit 8 Lesson 3 What Are Some Chemical Changes? Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 8 Lesson 3 What Are Some Chemical Changes? Signs of Change These clues tell us that a chemical change has taken place: Odor: Bacteria cause the bad smell of sour milk as they form new substance. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 8 Lesson 3 What Are Some Chemical Changes? Signs of Change color change: Sunlight shine son billboards, causing colors to chemically change and fade. Light: Light from a campfire or a firefly shows that chemical changes have taken place. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 8 Lesson 3 What Are Some Chemical Changes? Signs of Change Heat: Burning is a chemical reaction when materials burn, they give off heat. gas bubbles: Adding baking soda to vinegar causes gas bubbles to form. Bad smells, faded colors, heat and light from fires, and gas bubbles from adding vinegar to baking soda are all signs of chemical change. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 8 Lesson 3 What Are Some Chemical Changes? Copyright © Houghton Mifflin Harcourt Publishing Company

Signs of Change Unit 8 Lesson 3 What Are Some Chemical Changes? Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 8 Lesson 3 What Are Some Chemical Changes? Signs of Change A chemical reaction is another name for a chemical change. Chemical reactions can take place slowly or quickly. Copyright © Houghton Mifflin Harcourt Publishing Company

Signs of Change Certain substances can cause some chemical reactions to speed up, like stomach acid that helps you digest your food faster.

Making Pizza A chemical reaction is another name for chemical change. Unit 8 Lesson 3 What Are Some Chemical Changes? Making Pizza A chemical reaction is another name for chemical change. When you make pizza, several physical and chemical changes occur. Pushing and pulling the dough and cutting the vegetables are physical changes. The action of the yeast, the baking of the pizza, and the digestion of the pizza in your stomach are chemical changes. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 8 Lesson 3 What Are Some Chemical Changes? Copyright © Houghton Mifflin Harcourt Publishing Company