Physical and Chemical Changes

In the world around us, matter can undergo various transformations, resulting in either physical or chemical changes.

 Physical changes involve changes in the form or appearance of a substance without altering its chemical composition. On the other hand, chemical changes involve the rearrangement of atoms to form new substances with different properties.

Physical changes are usually reversible, meaning the original substance can be recovered.

Chemical changes, in contrast, are irreversible. Once a chemical change occurs, the original substances cannot be recovered.

Let’s explore the fundamental concepts and differences between physical and chemical changes.


Physical changes involve the alteration of a substance’s physical properties, such as shape, size, or state, without changing its chemical composition. These changes are often reversible and do not result in the formation of new substances. Here are some examples:

  • Melting
  • Freezing
  • Boiling
  • Condensation
  • Evaporation
  • Sublimation
  • Dissolving

Chemical changes, also known as chemical reactions, involve the transformation of one or more substances into entirely new substances. These changes occur at the molecular level, resulting in the breaking and formation of chemical bonds. Chemical changes are most often irreversible and accompanied by the release or absorption of energy. Some examples include:

  • Combustion
  • Oxidation
  • Reduction
  • Acid-base reactions
  • Precipitation
  • Decomposition
  • Synthesis