Physical changes involve a change in the physical properties of a substance, such as its shape, size, or state of matter, without changing its chemical composition. In the case of ice crystals forming on a window, water vapor in the air is condensing into a solid state (ice) without any change in its chemical composition.
On the other hand, chemical changes involve the transformation of one substance into one or more new substances with different chemical compositions. Chemical changes are often accompanied by changes in properties such as color, odor, or flammability. An example of a chemical change would be burning wood, where the wood undergoes a chemical reaction with oxygen to produce ash, water vapor, and carbon dioxide.
