Atoms are, put it how you want, “rearranged.” When a chemical reaction takes place bonds between atoms are broken and new ones are formed. Some of the signs of a chemical reaction are color change, temperature change, shape change, bubbling, smoking, etc. When bonds are being broken and formed, the atoms start to react with some of the other chemicals or ingredients.Also, during a chemical reaction, atoms are not created nor destroyed. Same goes for molecules, too. This is my knowledge and opinion on what really happens in a chemical reaction.