Types of Changes
Elementary School
Definition
The distinction between physical changes, which alter a substance's form without making a new substance, and chemical changes, which produce new substances. Melting ice is physical, while burning wood is chemical and cannot be easily reversed.
Worked examples
Ice melting into water at \(0\,^\circ\)C\(\)
A physical change — the substance stays H₂O, just switching between solid and liquid forms.
Wood burning in air to produce ash, carbon dioxide, and water vapor
A chemical change — new substances form, and you cannot reverse it to get the original wood back.
Sugar dissolving in tea
A physical change — the sugar molecules spread out but remain sugar; evaporate the water and you recover it.
Common mistakes
- Dissolving is always a chemical change because the substance disappears → Dissolving is a physical change; the substance is still there, just mixed You can recover dissolved salt or sugar by evaporating the water — no new substance formed.
- Rusting iron is physical because it just looks different → Rusting is chemical; iron reacts with oxygen to make iron oxide, a new substance Color change and new properties signal a chemical change, not just a shape or state shift.
- All physical changes are easy to reverse → Some physical changes are hard to reverse (e.g., shredding paper), but no new substance forms Reversibility helps identify change type, but the key test is whether the substance itself changes chemically.
Where you'll use it next
You'll use this distinction when studying chemical reactions, balancing equations, energy changes in reactions, and understanding conservation of mass in chemistry and environmental science.
See also
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026