Final answer:
Transmutation refers to the process of changing one element into another, accomplished naturally through radioactive decay or artificially using particle accelerators. It gained prominence in the early twentieth century with Rutherford's experiments and was a cornerstone of the Nuclear Age.
Step-by-step explanation:
Transmutation is the conversion of one chemical element or an isotope into another, which occurs due to a change in the number of protons within a nucleus. This can happen naturally through radioactive decay or artificially in a laboratory setting by bombarding a nucleus with particles. The concept of transmutation had a significant impact during the early twentieth century, following the discovery of radioactivity and the subsequent development of nuclear chemistry. The first successful artificial transmutation was conducted by Ernest Rutherford in 1919 when he bombarded nitrogen with alpha particles emitted by radium, thus transforming the nitrogen into oxygen and emitting a proton in the process.
Transmutation played a pivotal role both in peaceful applications, such as the generation of nuclear power, and in military uses, notably during World War II. To achieve the kinetic energies necessary for transmutation, scientists use particle accelerators, which propel nuclear particles using magnetic and electric fields in a vacuum to prevent collisions. Neutrons needed for these reactions are typically sourced from radioactive decay or nuclear reactors.