What is a Chemical Reaction?

There are two types of changes to matter Physical Change Chemical Change What’s the difference?

Physical Change A change to a substance’s form or appearance, but does not change into a new substance Examples: changes of state, cutting or bending, dissolving one substance into another, mixing substances together

So, what is a chemical reaction? A change that involve the breaking & reforming of bonds to create new substances. The result: a brand new substance is formed

Example #1 H2 + O2  H2O (water) Bonds break New bonds are formed

Example #2: Hydrochloric Acid Reactants: hydrogen gas (H2) + chlorine gas (Cl2) The bonds break Atoms rearrange Atoms form new bonds with each other. Product (New substance): Hydrogen chloride (HCl)

Parts of a Chemical Reaction In cooking, ingredients are combined to make food. In chemical reactions, reactants are combined to make products. The reactants are substances that are combined & changed in the reaction. The products are the new substances that result from the reaction.

A chemical reaction rearranges the atoms of the reactants to form new compounds of the products. No new atoms are created