Transmutation of elements

Nuclear transmutation is the conversion of one chemical element or an isotope into another. Because any element (or isotope of one) is defined by its number of protons (and neutrons) in its atoms, i.e. in the atomic nucleus, nuclear transmutation occurs in any process where the number of protons or neutrons in the nucleus is changed.

A transmutation can be achieved either by nuclear reactions (in which an outside particle reacts with a nucleus) or by radioactive decay where no outside cause is needed.

Although all transmutation is caused by either decay or nuclear reaction, not all of these processes cause transmutation. E.g., gamma decay, internal conversion do not transmute the affected atom, as it only a loss of energy.

Natural transmutation by stellar nucleosynthesis in the past created most of the heavier chemical elements in the universe, see the corresponding section below.

One type of natural transmutation observable in the present occurs when certain radioactive elements present in nature spontaneously decay by a process that causes transmutation, such as alpha or beta decay. An example is the natural decay of potassium-40 to argon-40, which forms most of the argon in the air. Also on Earth, natural transmutations from the different mechanisms of natural nuclear reactions occur, due to cosmic ray bombardment of elements (for example, to form carbon-14), and also occasionally from natural neutron bombardment (for example, see natural nuclear fission reactor).

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