* Chemical reactions involve the breaking and forming of bonds. This means the atoms within the starting materials (reactants) rearrange to form new molecules with different properties than the original materials.
* New substances have different chemical formulas. For example, when you burn wood, the wood (made of cellulose, sugars, and other compounds) reacts with oxygen in the air. The result is ash, carbon dioxide, water, and other products. These have different chemical formulas than the wood and oxygen you started with.
Here are some examples of chemical reactions that make new substances:
* Burning: Burning wood, paper, or gasoline all involve chemical reactions that create new substances, like ash, carbon dioxide, and water.
* Cooking: Baking a cake, frying an egg, or roasting vegetables involve chemical changes that alter the molecules in the food, creating new flavors and textures.
* Rusting: Iron reacts with oxygen in the air to form iron oxide, which is rust.
* Photosynthesis: Plants use sunlight, water, and carbon dioxide to create glucose (sugar) and oxygen.
Key takeaway: A chemical reaction is the process of rearranging atoms to form new molecules with different properties. This results in the formation of new substances.
