Transmutation is the conversion of one chemical element into another by changing the number of protons in an atomic nucleus. Transmutation occurs naturally through radioactive decay and nuclear reactions, and scientists can produce it artificially using nuclear reactors, particle accelerators, and other sources of nuclear particles.
The idea of transmutation is ancient. Alchemists famously sought ways to transform base metals into gold, although their chemical methods could not change one element into another. Modern nuclear physics eventually showed that elemental transmutation is real, but it requires a nuclear process rather than an ordinary chemical reaction.
Today, transmutation helps scientists produce radioactive isotopes, study nuclear reactions, understand the origin of the elements, generate nuclear energy, and investigate possible ways of reducing some forms of radioactive waste.
Key Takeaways: Transmutation
- Transmutation changes one chemical element into another by changing the number of protons in its nucleus.
- Ordinary chemical reactions cannot transmute elements because they rearrange electrons and atoms without changing atomic nuclei.
- Natural transmutation occurs through radioactive decay and naturally occurring nuclear reactions.
- Artificial or synthetic transmutation results from deliberately induced nuclear reactions.
- Ernest Rutherford demonstrated the first artificial transmutation in 1919 by converting nitrogen into oxygen through alpha-particle bombardment.
- Transmutation has applications in medicine, research, nuclear energy, isotope production, and potentially nuclear waste management.
- The alchemists’ dream of turning other elements into gold is physically possible, but it is impractical and far more expensive than obtaining natural gold.
What Is Transmutation?
In chemistry and nuclear physics, transmutation is the conversion of an atom of one chemical element into an atom of another element through a change in its atomic nucleus.
An element’s identity depends on its atomic number, which is the number of protons in its nucleus. Carbon always has 6 protons, nitrogen always has 7, oxygen always has 8, and gold always has 79.
Therefore, changing the number of neutrons alone does not cause elemental transmutation. It produces a different isotope of the same element. Transmutation occurs only when a nuclear process ultimately changes the number of protons.
For example, carbon-14 undergoes beta-minus decay:
¹⁴₆C → ¹⁴₇N + e⁻ + ν̅ₑ
The atomic number increases from 6 to 7, so carbon becomes nitrogen. This is transmutation.
In contrast, producing carbon-14 from carbon-13 by adding a neutron would change the isotope but not the element. Both nuclei still contain six protons.
Transmutation vs Nuclear Transformation
The terms nuclear transformation and transmutation sometimes overlap, but they are not necessarily identical.
A nuclear transformation is any process that changes an atomic nucleus. If the process changes only the number of neutrons, the product is a different isotope of the same element. If it changes the proton number, the process is also an elemental transmutation.
So, all elemental transmutations are nuclear transformations, but not every nuclear transformation is necessarily an elemental transmutation.
Why Transmutation Is Important
Transmutation is important because it demonstrates one of the fundamental differences between chemistry and nuclear physics.
Chemical reactions change how atoms share, gain, lose, or arrange electrons. The atomic nuclei remain essentially unchanged, so the identities of the elements remain the same. Burning carbon, for example, combines carbon with oxygen but does not convert carbon atoms into oxygen atoms.
Nuclear reactions operate at a deeper level. They change atomic nuclei and therefore can change the identities of elements themselves.
Understanding transmutation also explains:
- How radioactive elements decay
- How some radioactive isotopes form
- How stars and explosive astronomical events create elements
- How scientists manufacture useful radionuclides
- How nuclear reactors change their fuel
- How scientists synthesize elements that are rare or absent in nature
- How some proposed nuclear-waste treatments work
Transmutation also provided experimental evidence that elements are not immutable substances. Although atoms retain their identities during ordinary chemical reactions, their nuclei can change under the right conditions.
History of Transmutation
Alchemy and the Dream of Transmutation
The concept of transmutation predates modern chemistry by many centuries. Alchemists in Europe, the Islamic world, China, India, and other cultures investigated transformations of matter within broader philosophical and practical traditions.
European alchemy became particularly associated with chrysopoeia, the attempted transformation of base metals such as lead into gold. The legendary philosopher’s stone supposedly enabled this transformation and was also associated with other extraordinary properties.
Alchemy contributed techniques and apparatus that influenced the development of chemistry, including distillation, crystallization, extraction, and the preparation of various substances. However, alchemists had no means of altering atomic nuclei.
No combination of heating, mixing, dissolving, distilling, or other ordinary chemical processes can convert lead into gold.
Ironically, modern physics ultimately demonstrated that the central idea of elemental transmutation was possible, although not by the mechanism envisioned by alchemists.
Chemistry and the Idea of Immutable Elements
The development of modern chemistry changed the meaning of an element. Antoine Lavoisier’s work in the late 18th century helped establish a systematic chemical concept of elements, while John Dalton’s atomic theory in the early 19th century treated atoms of different elements as fundamentally distinct.
Within ordinary chemistry, elements appeared immutable. Chemical reactions could combine and separate elements, but they did not turn one element into another.
This principle became a foundation of classical chemistry.
Radioactivity Reveals Natural Transmutation
The discovery of radioactivity at the end of the 19th century changed this picture.
Henri Becquerel discovered radioactivity in uranium compounds in 1896. Marie and Pierre Curie subsequently investigated radioactive substances and discovered polonium and radium.
In the early 20th century, Ernest Rutherford and Frederick Soddy showed that radioactive decay involves the spontaneous transformation of one element into another. Their work established that radioactive elements form decay products with different chemical identities.
This was natural elemental transmutation.
For example, alpha decay reduces atomic number by two:
²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He
Uranium-238 becomes thorium-234.
The discovery was remarkable because it contradicted the long-standing assumption that atoms of one element could never become atoms of another.
Rutherford and the First Artificial Transmutation
In 1919, Ernest Rutherford reported the first artificial transmutation of an element.
Rutherford bombarded nitrogen with alpha particles and observed the emission of hydrogen nuclei, which were later recognized as protons. The net reaction is commonly written:
¹⁴₇N + ⁴₂He → ¹⁷₈O + ¹₁H
Nitrogen becomes oxygen.
This experiment demonstrated that humans could deliberately induce the conversion of one element into another.
Particle Accelerators, Reactors, and Synthetic Elements
Artificial transmutation expanded rapidly during the 20th century.
In 1932, John Cockcroft and Ernest Walton used accelerated protons to induce a nuclear reaction in lithium. Around the same period, the discovery of the neutron by James Chadwick provided a particularly useful particle for inducing nuclear reactions because neutrons carry no electric charge and therefore do not experience electrostatic repulsion from positively charged nuclei.
Enrico Fermi and others investigated neutron bombardment of elements during the 1930s. The discovery of nuclear fission in 1938–1939 revealed another major mechanism for transforming nuclei.
Nuclear reactors subsequently provided intense neutron fluxes for producing new isotopes and elements. Particle accelerators allowed scientists to bombard nuclei with protons, alpha particles, and heavier ions.
These techniques eventually led to the synthesis of transuranium and superheavy elements. Every element with an atomic number greater than uranium’s 92 was first produced artificially, although trace amounts of a few transuranium nuclides can also occur naturally.
How Transmutation Works
Transmutation works by changing the proton number of an atomic nucleus.
Several nuclear processes accomplish this.
Alpha Decay
In alpha decay, an unstable nucleus emits an alpha particle containing two protons and two neutrons.
The parent nucleus loses two protons, so its atomic number decreases by 2.
For example:
²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He
Uranium transmutes into thorium.
Beta-Minus Decay
During beta-minus (β⁻) decay, a neutron in the nucleus changes into a proton:
n → p + e⁻ + ν̅ₑ
The mass number remains unchanged, but the atomic number increases by 1.
For example:
¹⁴₆C → ¹⁴₇N + e⁻ + ν̅ₑ
Carbon transmutes into nitrogen.
Beta-Plus Decay
During beta-plus (β⁺) decay, a proton changes into a neutron while the nucleus emits a positron and an electron neutrino:
p → n + e⁺ + νₑ
The atomic number decreases by 1.
Electron Capture
During electron capture, the nucleus captures an inner atomic electron. A proton combines with the electron and becomes a neutron:
p + e⁻ → n + νₑ
The atomic number decreases by 1, producing a different element.
Nuclear Bombardment
A nucleus can also capture or interact with an incoming particle such as a:
- Neutron
- Proton
- Alpha particle
- Deuteron
- Heavy ion
The resulting compound nucleus may be unstable and emit one or more particles. If the final nucleus has a different number of protons, transmutation has occurred.
For example, Rutherford’s nitrogen reaction used an alpha particle:
¹⁴₇N + ⁴₂He → ¹⁷₈O + ¹₁H
Neutron Capture Followed by Radioactive Decay
Neutron capture is especially important in nuclear reactors and astrophysics.
Capturing a neutron alone does not change an element because the proton number stays the same. However, the resulting isotope may be radioactive and subsequently undergo beta decay.
A famous example occurs during the production of plutonium:
²³⁸₉₂U + ¹₀n → ²³⁹₉₂U
Uranium-239 then undergoes beta-minus decay:
²³⁹₉₂U → ²³⁹₉₃Np + e⁻ + ν̅ₑ
Neptunium-239 undergoes another beta-minus decay:
²³⁹₉₃Np → ²³⁹₉₄Pu + e⁻ + ν̅ₑ
The overall sequence transmutes uranium into plutonium.
Nuclear Fission
Nuclear fission splits a heavy nucleus into two smaller nuclei, usually accompanied by neutrons and energy.
Because the fission products are elements with different atomic numbers from the original nucleus, fission is a form of transmutation.
Nuclear Fusion
Nuclear fusion combines light nuclei into heavier nuclei. When the resulting nucleus belongs to a different element, fusion causes transmutation.
For example, one step in stellar hydrogen burning ultimately converts hydrogen nuclei into helium.
Fusion and other stellar nuclear reactions are responsible for producing many of the chemical elements found throughout the universe.
Natural Transmutation
Natural transmutation occurs without deliberate human intervention.
Radioactive Decay
Radioactive decay is one of the most familiar forms of natural transmutation. Uranium, thorium, radium, carbon-14, potassium-40, and many other radioactive nuclides eventually produce nuclei of other elements through alpha decay, beta decay, electron capture, or decay chains.
For example, the uranium-238 decay series passes through numerous elements before eventually reaching stable lead-206.
Cosmic-Ray Reactions
High-energy cosmic rays interact with atoms in Earth’s atmosphere and surface, producing nuclear reactions and new isotopes.
For example, cosmic-ray-generated neutrons contribute to the formation of carbon-14 from atmospheric nitrogen:
¹⁴₇N + ¹₀n → ¹⁴₆C + ¹₁H
Here, nitrogen transmutes into carbon.
Nuclear Reactions in Stars
Stars are enormous natural sites of nuclear transmutation.
Hydrogen fusion produces helium. Later stages of stellar evolution can produce progressively heavier nuclei. Neutron-capture processes and explosive environments such as supernovae and neutron-star mergers contribute to the formation of many elements heavier than iron.
Thus, most of the elements making up Earth, living organisms, and everyday materials ultimately owe their existence to ancient nuclear transmutation.
Natural Nuclear Reactors
Natural self-sustaining nuclear fission reactors operated roughly two billion years ago at Oklo, in what is now Gabon. Geological conditions allowed uranium deposits containing a higher proportion of uranium-235 than modern natural uranium to sustain nuclear chain reactions.
These reactions produced fission products and transmuted nuclides without human intervention.
Artificial or Synthetic Transmutation
Artificial transmutation is the deliberate conversion of one element into another by inducing a nuclear reaction.
Scientists accomplish this mainly using nuclear reactors and particle accelerators.
Transmutation in Nuclear Reactors
Reactors produce large numbers of neutrons. Nuclei can capture these neutrons and either undergo additional reactions or decay into other elements.
This process produces many useful radionuclides and also creates new elements within nuclear fuel.
Transmutation With Particle Accelerators
Particle accelerators propel charged particles to high energies and direct them at target nuclei.
Depending on the projectile and target, collisions can produce:
- New isotopes
- New elements
- Short-lived exotic nuclei
- Transuranium elements
- Superheavy elements
Many of the heaviest known elements are produced by accelerating nuclei of one element into nuclei of another and detecting the extremely small number of new nuclei formed.
Can Lead Really Be Turned Into Gold?
Yes, in principle, lead can be transmuted into gold.
Lead has atomic number 82, while gold has atomic number 79. A nuclear reaction that produces a stable or sufficiently long-lived nucleus containing 79 protons can therefore turn a lead nucleus into a gold nucleus.
Researchers have produced gold nuclei through nuclear reactions involving other elements, including mercury and lead.
However, this does not fulfill the alchemists’ dream in any practical sense. Such nuclear reactions typically require expensive accelerators or other nuclear facilities, produce tiny quantities, may produce radioactive isotopes, and cost vastly more than the resulting gold is worth.
Alchemy was therefore conceptually closer to reality than its practitioners could have known, but its chemical methods could never accomplish elemental transmutation.
Transmutation vs Chemical Reactions
The distinction between transmutation and chemical change is fundamental.
| Property | Chemical Reaction | Nuclear Transmutation |
|---|---|---|
| Main particles involved | Electrons | Atomic nuclei |
| Changes chemical bonds | Yes | Not necessarily |
| Changes atomic number | No | Yes |
| Changes element identity | No | Yes |
| Typical energy scale | Relatively low | Much higher |
| Example | 2 H₂ + O₂ → 2 H₂O | ¹⁴C → ¹⁴N + β⁻ |
Chemical reactions may dramatically change the properties of matter, but the elements themselves remain the same. Transmutation changes the identity of at least one element.
Conservation Laws in Transmutation
Nuclear transmutation does not mean matter changes arbitrarily. Nuclear reactions obey conservation laws.
When balancing a nuclear equation, two particularly useful quantities are:
Mass number (A): The total number of protons and neutrons must balance across a correctly written nuclear reaction when all participating nucleons are accounted for.
Atomic number (Z): Electric charge must be conserved.
Nuclear reactions also conserve total energy, momentum, angular momentum, and other relevant quantum quantities.
Mass by itself is not strictly conserved. Nuclear reactions convert small amounts of mass into energy or energy into mass according to:
E = mc²
This mass-energy relationship accounts for the energy released or absorbed in nuclear processes.
Applications and Uses of Transmutation
Production of Medical Radioisotopes
Nuclear reactions produce radionuclides used in medical imaging, diagnosis, and treatment.
Examples include isotopes used in positron emission tomography (PET), single-photon emission computed tomography (SPECT), and targeted radiation therapies.
Scientific Research
Artificial transmutation allows researchers to create unusual nuclei and study nuclear structure, radioactive decay, fundamental interactions, and the limits of nuclear stability.
Production of Synthetic Elements
Transmutation is essential for creating elements that do not exist naturally in useful quantities.
Particle accelerators have produced increasingly heavy elements, extending the periodic table through the superheavy elements.
Nuclear Energy
Transmutation occurs continuously inside nuclear reactors. Fuel nuclei undergo fission, while other nuclei capture neutrons and form new isotopes and elements.
For example, uranium-238 can ultimately produce plutonium-239 through neutron capture and beta decay.
Space Exploration and Power Sources
Some radioisotopes produced through nuclear reactions serve as heat or power sources for spacecraft. Radioisotope power systems use energy released by radioactive decay to support missions where sunlight is weak or unreliable.
Nuclear Waste Management
Transmutation has been investigated as a method for reducing the long-term radiotoxicity of some nuclear waste.
Certain long-lived actinides and fission products could potentially be bombarded with neutrons so that they transform into shorter-lived or stable nuclides.
Proposed systems include fast reactors and accelerator-driven systems (ADS).
Transmutation does not make all nuclear waste disappear. Instead, it potentially changes the composition of selected waste streams and may reduce some long-term disposal challenges. It also requires separation, irradiation, specialized facilities, and careful management of the resulting materials.
Transmutation and the Origin of the Elements
Transmutation is central to nucleosynthesis, the formation of atomic nuclei.
The early universe produced mostly hydrogen and helium, with small amounts of a few other light nuclides. Stars subsequently transformed lighter nuclei into heavier ones through fusion and related nuclear reactions.
Elements heavier than iron generally require processes involving neutron capture, proton capture, photodisintegration, or other reactions associated with particular stellar and explosive environments.
Two especially important neutron-capture mechanisms are:
s-process (slow neutron capture): Occurs when neutron capture is slow compared with radioactive beta decay and contributes to the formation of many heavy nuclei in evolved stars.
r-process (rapid neutron capture): Occurs under extremely neutron-rich conditions and produces many of the heaviest nuclei. Neutron-star mergers are confirmed r-process sites, while some rare explosive stellar events may also contribute.
In this sense, transmutation is not merely a laboratory phenomenon. It is one of the processes responsible for the chemical composition of the universe.
Other Meanings of Transmutation
The word transmutation has meanings outside modern nuclear chemistry and physics, so context matters.
Alchemy: Transmutation historically referred to converting one substance or element into another, particularly the attempted conversion of base metals into gold.
Biology: Older biological literature sometimes uses transmutation for supposed transformations of one species or form of life into another. The term appeared in historical discussions of evolutionary ideas before modern evolutionary terminology became established. Modern evolutionary biology generally does not use transmutation as the standard term for evolution.
General or philosophical use: Transmutation may simply mean a profound transformation from one state, form, or nature into another.
In modern science, an unqualified reference to elemental transmutation usually concerns a nuclear process that converts one chemical element into another.
Common Misconceptions About Transmutation
Misconception: Chemical reactions can change one element into another.
Chemical reactions rearrange electrons and chemical bonds. They do not normally change the number of protons in atomic nuclei, so they do not transmute elements.
Misconception: Changing an isotope is always transmutation.
Not necessarily. Adding or removing neutrons can change one isotope into another while leaving the atomic number unchanged. In the strict elemental sense, transmutation requires a change in proton number.
Misconception: Alchemists successfully transmuted metals.
There is no evidence that alchemists converted one chemical element into another. Their chemical methods were incapable of changing atomic nuclei.
Misconception: The alchemists’ goal violates the laws of physics.
Elemental transmutation itself is physically possible. The problem was the proposed method. Nuclear reactions can produce gold; chemical procedures cannot.
Misconception: Transmutation only happens artificially.
Natural radioactive decay, stellar nucleosynthesis, cosmic-ray reactions, and other natural nuclear processes continuously transmute elements.
Misconception: Radioactive decay always causes transmutation.
Some radioactive processes change atomic number and therefore transmute the element, but not every nuclear decay does. Gamma decay, for example, lowers the energy of a nucleus without changing its numbers of protons or neutrons, so the element remains unchanged.
Misconception: Transmutation can eliminate nuclear waste completely.
Transmutation may reduce particular long-lived radioactive components, but it does not simply make nuclear waste vanish. It creates other nuclides and must be considered as part of a broader waste-management strategy.
Frequently Asked Questions
What is transmutation in simple terms?
Transmutation is the conversion of one chemical element into another by changing the number of protons in its atomic nucleus.
What causes transmutation?
Transmutation results from nuclear processes such as alpha decay, beta decay, electron capture, nuclear fission, nuclear fusion, or particle-induced nuclear reactions.
What is the difference between natural and artificial transmutation?
Natural transmutation occurs without deliberate human intervention, such as during radioactive decay or nuclear reactions in stars. Artificial transmutation occurs when people deliberately induce nuclear reactions using reactors, accelerators, or other equipment.
Who discovered transmutation?
Ernest Rutherford and Frederick Soddy established that radioactive decay involves the natural transmutation of elements in the early 20th century. Rutherford later demonstrated the first artificial transmutation in 1919 by bombarding nitrogen with alpha particles.
What was the first artificial transmutation?
Rutherford bombarded nitrogen-14 with alpha particles, producing oxygen-17 and a proton:
¹⁴₇N + ⁴₂He → ¹⁷₈O + ¹₁H
Can one element really turn into another?
Yes. If a nuclear process changes the number of protons in an atom’s nucleus, the atom becomes a different element.
Can lead be turned into gold?
Yes, nuclear reactions can in principle convert lead nuclei into gold nuclei. However, producing gold this way is technologically difficult, inefficient, and vastly more expensive than the gold produced.
Is radioactive decay a form of transmutation?
It is when the decay changes atomic number. Alpha decay, beta-minus decay, beta-plus decay, and electron capture can cause elemental transmutation. Gamma decay does not change atomic number and therefore does not transmute the element.
Is nuclear fission transmutation?
Yes. Fission converts a heavy nucleus into nuclei of different elements, so it is a form of elemental transmutation.
Is nuclear fusion transmutation?
Yes, when fusion produces a nucleus with a different atomic number. Hydrogen fusion into helium in stars is a familiar example.
Does neutron capture cause transmutation?
Not by itself. Capturing a neutron changes the isotope but leaves the atomic number unchanged. However, the new isotope may undergo beta decay or another reaction that changes its proton number, resulting in transmutation.
Does transmutation occur inside the human body?
Yes, but only at extremely low levels under ordinary circumstances. Naturally occurring radioactive isotopes within the body undergo nuclear decay, and some decay processes transmute atoms into other elements. These events have essentially nothing to do with ordinary biochemical reactions.
Summary
Transmutation is the conversion of one chemical element into another through a nuclear process that changes the number of protons in an atomic nucleus. It occurs naturally through radioactive decay, cosmic-ray interactions, and nuclear reactions in stars, and it can be induced artificially using nuclear reactors and particle accelerators.
The concept has an unusual history. For centuries, alchemists attempted to transform base metals into gold using chemical methods. Modern chemistry showed why those methods could not succeed, while 20th-century nuclear physics revealed that elemental transmutation itself is real.
Today, transmutation is fundamental to nuclear physics, astrophysics, nuclear energy, isotope production, medicine, and the synthesis of new elements. It also provides a striking reminder that while chemical elements retain their identities during ordinary chemical reactions, atomic nuclei themselves are capable of profound change.
References and Further Reading
- Barzakh, A.E.; Andreyev, A.N.; Atanasov, D.; et al., Isolde collaboration (2022). “Producing gold at ISOLDE-CERN”. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. 513: 26–32. doi:10.1016/j.nimb.2021.12.011
- Lehmann, W.M. (2000). “Transmutation in der Kerntechnik” [Nuclear Transmutation]. Elektrizitaetswirtschaft (in German). 99 (1–2). Frankfurt am Main: VWEW-Energieverlag GmbH: 51–52. ISSN 0013-5496. INIS 31018687
- R. Sherr; K. T. Bainbridge; H. H. Anderson (1941). “Transmutation of Mercury by Fast Neutrons”. Physical Review. 60 (7): 473–479. doi:10.1103/PhysRev.60.473