Middle School
Chemical Changes
Chemical reactions, conservation of mass, energy changes, and designing solutions with reactions.
MS-PS1-2, MS-PS1-5, MS-PS1-6
2 lessons
4 quiz questions
Lesson 1: Evidence of Chemical Reactions
Identify signs that new substances formed.
Learning goals
- Distinguish physical and chemical changes.
- Identify evidence of reactions.
- Explain that atoms rearrange during reactions.
New substances
In a chemical reaction, atoms rearrange to form new substances with different properties. Evidence may include gas production, temperature change, color change, light, odor, or a precipitate.
Physical versus chemical
A physical change alters form or state without making new substances. A chemical change produces new substances.
Lesson 2: Conservation and Energy
Track atoms, mass, and energy during reactions.
Learning goals
- Explain conservation of mass.
- Model atoms before and after reactions.
- Compare reactions that absorb or release energy.
Atoms are conserved
Atoms are not created or destroyed in ordinary chemical reactions. They rearrange, so the total number of each type of atom stays the same.
Energy changes
Some reactions release energy, making surroundings warmer or producing light. Other reactions absorb energy, making surroundings cooler.