rare radioactive natural elements; often produced artificially
a synthetic element is one of 24 chemical elements that do not occur naturally on earth: they have been created by human manipulation of fundamental particles in a nuclear reactor or particle accelerator, or explosion of an atomic bomb; thus, they are called "synthetic", "artificial", or "man-made". the synthetic elements are those with atomic numbers 95–118, as shown in purple on the accompanying periodic table: these 24 elements were first created between 1944 and 2010. the mechanism for the creation of a synthetic element is to force additional protons onto the nucleus of an element with an atomic number lower than 95. all synthetic elements are unstable, but they decay at a widely varying rate: their half-lives range from 15.6 million years to a few hundred microseconds.
seven other elements that were created artificially—and thus initially considered to be synthetic—were later discovered to exist in nature in trace quantities. the first, technetium, was created in 1937. plutonium, atomic number 94, first synthesized in 1940, is another such element. it is the element with the largest number of protons (and equivalent atomic number) to occur in nature, but it does so in such tiny quantities that it is far more practical to synthesize it. plutonium is extremely well-known due to its use in atomic bombs and nuclear reactors. no elements with an atomic number greater than 99 have any uses outside of scientific research, since they have extremely short half-lives, and thus have never been produced in large quantities.