What signifies a chemical change in a substance?

A chemical change in a substance is signified by the formation of new substances with different properties than the original materials. The presence of a symbol delta often indicates a reaction that has taken place, reflecting a change in the chemical composition of the substance. When a delta is used, it typically represents that energy is being added to or removed from a system during the reaction, which is a crucial aspect of many chemical processes.

In contrast, a change in state of matter refers to physical changes, such as ice melting to water, which do not alter the chemical composition of the substances involved. A color change without a reaction may occur in some physical processes and does not necessarily indicate a chemical change, as it could simply represent a physical state or mixture. Lastly, a change in temperature alone is not definitive of a chemical reaction; it can also occur during physical changes. Therefore, the symbol delta is a strong indicator of chemical changes involving energy transfer and the creation of new products.