A chemical change, also known as a chemical reaction, is a process in which one or more substances (called reactants) are transformed into one or more different substances (called products) with new chemical properties. This transformation involves the rearrangement of atoms and the breaking and forming of chemical bonds, resulting in substances that have different characteristics from the original ones

. Key features of a chemical change include:

• Formation of new substances with different properties.
• Irreversibility under normal conditions (the original substances cannot easily be recovered without further chemical reactions).
• Accompanied by energy changes, such as heat being released (exothermic) or absorbed (endothermic).
• Possible observable signs such as color change, temperature change, gas production (bubbles), formation of a precipitate, odor change, or light emission

Examples of chemical changes are burning wood, rusting iron, cooking an egg, and mixing baking soda with vinegar. These changes contrast with physical changes, where no new substances are formed and the original material remains chemically the same, such as breaking glass or melting ice

. In summary, a chemical change is a fundamental chemical reaction where substances are chemically altered to produce new substances with different properties, often accompanied by observable signs and energy changes