Physical or Chemical?
Class 7 Science: physical and chemical changes
Sort everyday changes: is a new substance made, or is it the same stuff in a new shape or state?
Words to know
- Physical change
- Shape, size or state changes, but no new substance forms.
- Chemical change
- One or more new substances form.
- Reversible
- Can be undone, like melting and freezing ice.
- Rusting
- Iron reacting with oxygen and water to form rust.
Quick check
Answer 3 questions to check what you learned.
Try at home
Leave an iron nail in a little water for a week (ask an adult). Keep another nail dry. Which one rusts? Rusting needs both air and water.