Page 2 - 3-Lesson Notes-Physical change, Chemical change and their properties

• A temporary change in colour may take place.

• Very little energy (heat) is absorbed or released.
➢ Remember, the appearance of matter changes in a physical change, but its chemical

identity remains the same.

CHEMICAL CHANGES:

➢ The changes that take place in the chemical properties of a substance due to molecular

changes and new substances are formed. E.g., burning wood, rotten fruits, and

vegetables, fireworks, rusted iron, etc.
➢ Chemical changes are usually permanent, which results in the formation of new

substances with composition and properties different from those of the original substance.
➢ Chemical changes are also called Chemical Reactions.

➢ A chemical change (chemical reaction) takes place when two substances react chemically

to form a new substance with different chemical properties.
➢ The substances that undergo a chemical change are called Reactants.

➢ The new substances formed during a chemical change are called Products.
➢ A lot of energy (in form of heat, light, sound, etc.) is either absorbed or released during

chemical changes.

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