Computer science, engineering, and medicine are applied sciences. They build on already-established scientific principles to devise practical applications in the real world. In other words, it uses the information that comes from other scientific research to improve technology and invent things.

Chemistry is a natural science, because it studies things that occur without help from humans. Natural sciences, such as chemistry and physics, exist to provide knowledge through research.

Knowledge within the natural sciences is based on what can be observed and confirmed by other researchers working under similar conditions. Applied science deals with using the natural sciences and the formal sciences, like mathematics, logic, and statistics.

Chemistry deals primarily with the 94 chemical elements that are found in nature, from hydrogen—the lightest, with one proton in the nucleus and one electron in orbit around it—to plutonium, the heaviest, with 94 protons and a "cloud" of 94 electrons.

There are also 24 "synthetic" elements, which are created in laboratories and exist only for fractions of a second. Although these are not found in nature, they are chemical elements and are studied in chemistry.

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