Physical and Chemical Changes in Matter

A physical change is a change that affects one or more physical properties of a substance without altering its chemical composition. Examples include changes in state (like melting or freezing) and changes in shape or size.

A chemical change is a change that results in the formation of new chemical substances. It involves a chemical reaction and includes changes such as burning, rusting, or digestion.

Physical properties are characteristics of a substance that can be observed or measured without changing the substance's chemical identity. Examples include color, odor, melting point, and density.

Chemical properties describe a substance's ability to undergo changes that transform it into different substances. Examples include reactivity with acids, flammability, and oxidation states.

Indicators of a chemical change include color change, formation of a precipitate, formation of gas/bubbles, and temperature change.

The formation of a precipitate indicates a chemical change, as it shows that a new substance has formed from the reaction of two or more substances.

An example of a physical change is ice melting into water. The substance remains H2O, but its state changes from solid to liquid.

An example of a chemical change is the burning of wood. The wood reacts with oxygen to form ash, carbon dioxide, and water, creating new substances.

During photosynthesis, plants convert carbon dioxide and water into glucose and oxygen using sunlight. This process is a chemical change.

A physical change alters the form or appearance of a substance without changing its chemical composition, while a chemical change results in the formation of new substances.