* New Substance Formed: Sodium (Na) and chlorine (Cl) are both elements. When they react, they form a completely new compound, sodium chloride (NaCl), which has entirely different properties than either sodium or chlorine.
* Chemical Bonds: The reaction involves the breaking of existing bonds in the sodium and chlorine atoms and the formation of new ionic bonds between sodium and chlorine atoms. This is a fundamental characteristic of chemical changes.
* Energy Release: The reaction between sodium and chlorine is highly exothermic, releasing a significant amount of heat and light. This energy release is another strong indicator of a chemical change.
In contrast, a physical change would involve altering the form or appearance of a substance without changing its chemical composition. For example, melting ice is a physical change because the water molecules (H₂O) remain the same, even though the state of matter changes.
