It is a physical change because the atoms are not rearranged into a different substance.
For a chemical change to occur one or more of the following must happen:
- A solid separates from a liquid mixture
- gas bubbles are released or an explosion of burning gases occurs
- A substance's color changes, usually permanently.
*This can occur with either physical or chemical changes
- the temperature changes, or
- Light, sound , or another type of energy is produced.
Breaking of glass is not a chemical change because a new substance is not formed.
Basically, a chemical change is when a new substance is formed no matter how it's formed.
And in this scenario, a new substance is not formed, glass is just broken into smaller pieces.