Wiktionary
n. (context chemistry English) any process in which reactants are changed into products by the breaking or creation of chemical bonds
WordNet
n. (chemistry) any process determined by the atomic and molecular composition and structure of the substances involved [syn: chemical process, chemical action]
Wikipedia
Chemical changes occur when a substance combines with another to form a new substance, called synthesis or, alternatively, decomposes into two or more different substances. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. Some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. Understanding chemical changes is a major part of the science of chemistry.
When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an energy change as new products are generated. An example of a chemical change is the reaction between sodium and water to produce sodium hydroxide and hydrogen. So much energy is released that the hydrogen gas released spontaneously burns in the air. This is an example of a chemical change because the end products are chemically different from the substances before the reaction.
Usage examples of "chemical change".
The rods contain a rose-colored visual pigment and it is that which actually undergoes the chemical change with light.
Ostwald at the beginning of the present century, when he stated that the chemical element represents a condition of physical matter in which 'any chemical change results in an increase of weight'.
Up until the 1960s, it was assumed that sticking was either a mechanical operation, involving the dovetailing or interlocking of molecular structures, or a chemical change that formed new chemical bonds.
Grog does not regain plasticity and will not undergo chemical change when re-fired.
We know from the strong odour of cooked cabbageleaves that boiling water produces some chemical change in them, and that they are thus rendered far more digestible and nutritious to man.
They produce an electro-chemical change in everything but the bony structure of the body.
The very process of combining had been transformed so that there was now physical change, chemical change, chain reaction, chemical reaction, and fusion, to name but a few.
Were you using some special kind of pigments that make a chemical change?
The tremendous heat forced a chemical change in his living substance, causing it to lose cohesion.
He had talked excitedly of some organic compound of gold being the catalyst he had sought for months to speed up the chemical change in the ripening fruit.
Out of the water, though, it died in minutes and dried out quickly, causing its natural internal fluids to undergo a chemical change, crystallize, and become a very sweet and addicting drug that could be eaten, injected, or who knew what else?
The impression of a receding picture, which observers also had noticed, had been caused by the chemical change in the air.
As he exerted his tremendous strength a chemical change seemed to come over his body.
There has been no organic or chemical change inside since this was sealed.