In chemistry, reactants are the substances that start a chemical reaction. Products are the new substances that are created after the reaction happens.

Example:

• Reactants: Hydrogen gas (H₂) and oxygen gas (O₂)
• Reaction: When these two gases come together, they form water (H₂O).

Here are some signs that a chemical reaction is happening:

• Color Change: This is like when an apple turns brown.
• Gas Production: For example, when you mix baking soda with vinegar, it makes bubbles.
• Temperature Change: A hot pack that heats up is another example.

These signs help us see that a chemical reaction is taking place!