chemical change

In a chemical change, bonds are broken and new bonds are formed between different atoms. This breaking and forming of bonds takes place when particles of the original materials collide with one another. Some exothermic reactions may be hot enough to cause certain chemicals to also undergo a change in state; for example in the case of aqueous solutions, bubbles may not necessarily be newly produced gas but instead water vapor.
Whenever chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an energy change; new products are generated. An example of a chemical change is the reaction between sodium and chlorine to produce sodium chloride, or table salt. This reaction is so exothermic, meaning it releases heat in the form of energy, that even flames are generated. This is an example of a chemical change because the end product is molecularly different from the starting molecules.
Chemical changes are happening all the time. There are several different types of chemical change, including: synthesis, decomposition, single displacement, double displacement, neutralization, precipitation, combustion, redox and wood burning.
A primary example chemical change is the combustion of methane to produce carbon dioxide and water.
Other examples of chemical changes are:
Mixing an acid with a base, producing water and a salt.
Photosynthesis - a process in which carbon dioxide and water are changed into sugars by plants.
Cracking heavy hydrocarbons to create lighter hydrocarbons (part of the process of refining oil).
Cooking examples: cake, pancakes, and eggs etc.
Oxidation examples: rust or tarnishing
Ripening examples: bananas, tomatoes