noun, plural: chemical reactions
A process in which one or more substances (reactants) are chemically changed into one or more new substances (products). Chemical changes may involve motion of electrons in the forming and breaking of chemical bonds.
Word origin: chemical: from New Latin chimicus, from Medieval Latin alchimicus, from alchymia, alchemy; reaction: from re-, again, + action, from Latin actio, noun of action form from perfect passive participle actus, done, from verb agere, do.
A few sentences, just in case, that has the word 'chemical reaction' are:
1.) A chemical reaction that is very easily created are Liquid -> Gas.