Nuclear Reactions — Transforming the Atom's Core
25 reacciones
Nuclear reactions involve changes to an atom's nucleus — fundamentally different from chemical reactions, which only rearrange electrons. Nuclear reactions convert one element into another (transmutation), release or absorb enormous amounts of energy, and involve particles like alpha particles, beta particles, neutrons, and gamma rays. The energy involved in nuclear reactions is millions of times greater per atom than in chemical reactions, governed by Einstein's mass-energy equivalence E = mc2.
Mecanismo de reacción
Nuclear fission splits heavy nuclei (uranium-235, plutonium-239) into lighter fragments when struck by a neutron, releasing 2-3 additional neutrons that can trigger a chain reaction. Each fission event releases about 200 MeV of energy — roughly 50 million times more than burning one molecule of octane. Nuclear fusion combines light nuclei (hydrogen isotopes deuterium and tritium) into helium, releasing even more energy per unit mass. Radioactive decay is spontaneous nuclear transformation — alpha decay reduces atomic number by 2, beta decay converts a neutron to a proton (or vice versa).
Ejemplos cotidianos
Smoke detectors use americium-241 alpha decay. Carbon-14 dating measures the radioactive decay of carbon-14 in organic materials to determine age — reliable up to about 50,000 years. Medical PET scans use positron-emitting isotopes (fluorine-18) to image metabolic activity in the body. Bananas contain potassium-40, a naturally radioactive isotope.
Importancia industrial
Nuclear power generates approximately 10 percent of global electricity from about 440 reactors in 32 countries, producing minimal CO2 during operation. Nuclear medicine uses over 40 million procedures annually for diagnosis and treatment. Industrial radiography uses gamma sources to inspect welds in pipelines and aircraft. Research reactors produce medical isotopes like technetium-99m, used in 80 percent of nuclear medicine procedures.
Safety Note
Radioactive materials require specialized shielding, monitoring, and handling protocols. Alpha particles are stopped by paper but lethal if ingested. Beta and gamma radiation require denser shielding. Follow ALARA (As Low As Reasonably Achievable) principles for radiation exposure. Nuclear waste disposal remains a major environmental and engineering challenge.
Cadena protón-protón (fusión solar)
4¹H → ⁴He + 2e⁺ + 2νₑ + energy
The proton-proton chain converts four hydrogen nuclei into one helium-4 nucleus, two positrons, and two electron neutrinos in a multi-step …
Captura electrónica por berilio-7
⁷Be + e⁻ → ⁷Li + νₑ
Beryllium-7 captures an inner orbital electron, converting a proton to a neutron and producing lithium-7 and a neutrino. This electron …
Captura neutrónica por uranio-238
²³⁸U + ¹n → ²³⁹U → ²³⁹Np → ²³⁹Pu
Uranium-238 captures a neutron to form uranium-239, which beta decays (23.5 min) to neptunium-239, which beta decays (2.36 days) to …
Desintegración alfa del americio-241
²⁴¹Am → ²³⁷Np + ⁴He
Americium-241 alpha decays to neptunium-237 with a half-life of 432 years, also emitting a 59.5 keV gamma ray. Am-241 is …
Desintegración alfa de polonio-210
²¹⁰Po → ²⁰⁶Pb + ⁴He
Polonium-210 alpha decays to stable lead-206 with a half-life of 138 days. Po-210 emits a 5.3 MeV alpha particle and …
Desintegración alfa de radio-226
²²⁶Ra → ²²²Rn + ⁴He
Radium-226 emits an alpha particle to form radon-222 gas. Radium was discovered by Marie and Pierre Curie in 1898 and …
Desintegración alfa de radón-222
²²²Rn → ²¹⁸Po + ⁴He
Radon-222, a radioactive noble gas, alpha decays to polonium-218 with a half-life of 3.82 days. As the densest naturally occurring …
Desintegración alfa de torio-232
²³²Th → ²²⁸Ra + ⁴He
Thorium-232 alpha decays to radium-228 with a half-life of 14.05 billion years, longer than the age of the universe. Thorium …
Desintegración alfa de uranio-238
²³⁸U → ²³⁴Th + ⁴He
Uranium-238 emits an alpha particle (helium-4 nucleus) to become thorium-234. This is the first step in the uranium-238 decay series, …
Desintegración beta de carbono-14
¹⁴C → ¹⁴N + e⁻ + ν̄ₑ
Carbon-14 undergoes beta-minus decay to nitrogen-14, emitting an electron and an antineutrino. C-14 has a half-life of 5,730 years and …
Desintegración beta de cesio-137
¹³⁷Cs → ¹³⁷Ba + e⁻ + ν̄ₑ + γ
Cesium-137 beta decays to barium-137m (metastable), which then emits a 662 keV gamma ray to reach stable barium-137. Cs-137 has …
Desintegración beta de cobalto-60
⁶⁰Co → ⁶⁰Ni + e⁻ + ν̄ₑ + γ
Cobalt-60 beta decays to nickel-60 with emission of two gamma rays (1.17 and 1.33 MeV) and an electron. The 5.27-year …
Desintegración beta de estroncio-90
⁹⁰Sr → ⁹⁰Y + e⁻ + ν̄ₑ
Strontium-90 undergoes beta decay to yttrium-90 with a half-life of 28.8 years. Sr-90 is a major fission product and is …
Desintegración beta del tritio
³H → ³He + e⁻ + ν̄ₑ
Tritium (hydrogen-3) undergoes beta decay to helium-3 with a half-life of 12.3 years, emitting a very low energy electron (max …
Desintegración beta de potasio-40
⁴⁰K → ⁴⁰Ca + e⁻ + ν̄ₑ
Potassium-40 decays to calcium-40 by beta emission (89.3%) or to argon-40 by electron capture (10.7%). With a half-life of 1.25 …
Desintegración beta de yodo-131
¹³¹I → ¹³¹Xe + e⁻ + ν̄ₑ + γ
Iodine-131 beta decays to xenon-131 with a half-life of 8.02 days, also emitting gamma radiation. I-131 concentrates in the thyroid …
Desintegración gamma del tecnecio-99m
⁹⁹ᵐTc → ⁹⁹Tc + γ
Technetium-99m (metastable) releases a 140 keV gamma ray to reach the ground state Tc-99 with a half-life of 6.01 hours. …
Emisión de positrones del carbono-11
¹¹C → ¹¹B + e⁺ + νₑ
Carbon-11 undergoes positron emission to become boron-11 with a short half-life of 20.4 minutes. C-11 can be incorporated into virtually …
Emisión de positrones del flúor-18 (PET)
¹⁸F → ¹⁸O + e⁺ + νₑ
Fluorine-18 undergoes positron emission to become oxygen-18 with a half-life of 109.8 minutes. The emitted positron annihilates with an electron, …
Fisión del plutonio-239
²³⁹Pu + ¹n → ¹³⁴Xe + ¹⁰³Zr + 3¹n
Plutonium-239 undergoes neutron-induced fission similar to U-235 but with slightly higher energy release. Pu-239 is produced in reactors when U-238 …
Fisión del uranio-235
²³⁵U + ¹n → ¹⁴¹Ba + ⁹²Kr + 3¹n
A uranium-235 nucleus absorbs a slow neutron and splits into barium-141 and krypton-92, releasing three neutrons and approximately 200 MeV …
Fusión deuterio-deuterio
²H + ²H → ³He + ¹n
Two deuterium nuclei fuse to produce helium-3 and a neutron, releasing 3.27 MeV. An alternative D-D reaction produces tritium and …
Fusión deuterio-tritio
²H + ³H → ⁴He + ¹n
Deuterium and tritium fuse at temperatures exceeding 100 million degrees to form helium-4 and a neutron, releasing 17.6 MeV of …
Proceso triple alfa (combustión del helio)
3⁴He → ¹²C + γ
Three helium-4 nuclei fuse to form carbon-12 in stars through the triple-alpha process, which occurs above 100 million K. Two …
Transmutación nuclear de Rutherford
¹⁴N + ⁴He → ¹⁷O + ¹H
In 1919, Ernest Rutherford achieved the first artificial nuclear transmutation by bombarding nitrogen-14 with alpha particles to produce oxygen-17 and …