Changing Matter

Chemical reactions happen when substances interact and change into new substances. Atoms are rearranged, but the total amount of matter stays the same.

Signs of a Chemical Reaction

• Color change
• Gas production (bubbles)
• Temperature change
• Formation of a solid (precipitate)

The Law of Conservation of Mass

In any chemical reaction, mass is neither created nor destroyed. The total mass of the reactants always equals the total mass of the products.

\( \text{Reactants} \rightarrow \text{Products} \)

Real-World Uses

Chemical reactions power batteries, digest our food, and are behind fireworks and baking!

Balancing Equations

To show that mass is conserved, chemical equations must be balanced—meaning the number of each type of atom is the same on both sides.