Evidence of a Chemical Reaction

• If we could see the atoms and molecules that compose matter, we could easily identify a chemical reaction:

• Atoms combine with other atoms to form compounds.

• New molecules form.

• The original molecules decompose.

• Atoms in one molecule change places with atoms in another.

• If we could see the atoms and molecules that compose matter, we could know a chemical reaction has occurred by observing these changes.

• Often, these molecular changes cause macroscopic changes that we can directly experience.