Changes of state are examples of physical changes. No new substances are made, and the change is often easily reversed. For example:
Chemical changes are different from physical changes. New substances are made in chemical changes, and the change is often not easily reversed. Chemical changes involve chemical reactions and include:
In a chemical change, particles separate from one another and then join together in different ways to before.
This diagram shows what happens to iron and sulfur particles in a chemical reaction to form iron:
Explain how the particle diagram shows that a chemical change happens.
To begin with, iron particles are only joined to other iron particles, and sulfur particles are only joined to other sulfur particles. After the chemical change, iron particles and sulfur particles are joined to each other.