* New substances are formed: The proteins in the egg white and yolk undergo denaturation when heated. This means their structure changes, forming new chemical bonds and creating new substances. This is why a raw egg is runny and transparent, while a cooked egg is solid and opaque.
* Irreversible: You can't reverse the cooking process to get back a raw egg. The changes in the egg's protein structure are permanent.
Other signs of a chemical change:
* Color change: The egg white turns white, and the yolk can become more yellow.
* Smell change: A cooked egg has a different odor than a raw egg.
In contrast, a physical change only alters the form or appearance of a substance, not its chemical composition. For example, cracking an egg is a physical change.
