The highest level of scientific experiment is known as experimental, or randomized control. In this type, as the name implies, there is the greatest amount of control. There are at least two groups used in this type of scientific experiment. Each group is made up of subjects that resemble each other as close as possible, such as by age, gender, etc. Subjects can be human, animal or the environment.
Chemical changes can result from the combination of different substance through a reaction to give one or more different substances. Decomposition, the opposite of combination, involves the breakdown of a single substance into two or more different substances.
Chemical properties are characteristics of a material that become evident when the material undergoes a chemical reaction or chemical change. People cannot observe chemical properties by simply viewing or touching a sample of the material; the actual structure of the material must be changed in order for people to observe the chemical properties.