Nuclear chemistry
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- Written by: Germán Fernández
- Category: nuclear chemistry
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With the exception of hydrogen and helium that were generated during the Big Bang, the rest of the chemical elements have been formed in stars. Nuclear fusion joins the nuclei of light elements to create heavier ones.
Atoms with heavy nuclei (atomic number greater than 83) are unstable and tend to emit particles to transform into lighter and more stable elements. Not only are the heavy elements radioactive, the isotope of carbon (carbon-14) disintegrates emitting beta particles (electrons) that transform it into nitrogen-14. This property is used in the dating of samples derived from living beings.
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- Written by: Germán Fernández
- Category: nuclear chemistry
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Alpha particles are helium-4 nuclei, made up of two protons and two neutrons. These particles are ejected by large nuclei, but they can also be used as projectiles to bombard nuclei and trigger nuclear processes.
Alpha particles are positively charged and are deflected by electric and magnetic fields. Their penetrating power that low, being stopped by a sheet of paper.
The following nuclear equation represents the emission of alpha particles by a uranium-238 nucleus with formation of thorium-234.
\begin{equation} ^{238}_{92}U\rightarrow ^{234}_{90}Th+^{2}_{4}He \end{equation} As can be seen, the sum of atomic and mass numbers coincides on both sides of the reaction.
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- Written by: Germán Fernández
- Category: nuclear chemistry
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Beta particles ($\beta$) are electrons, therefore they have a negative charge and are deflected by electric and magnetic fields in the opposite direction to alpha particles. These electrons that some atoms emit originate in the atomic nucleus, through the transformation of a proton into a neutron. Nuclei with a high proton/neutron ratio emit beta particles to stabilize themselves.
Beta particles are represented by the symbol $^{0}_{-1}\beta$, indicating that they have a zero mass number (it has a mass much less than the proton and neutron) and the equivalent of an atomic number of -1 . The beta emission requires the release of another particle called a neutrino ($\nu$), leaving the nuclear equation as follows. \begin{equation} ^{1}_{0}n\rightarrow ^{1}_{1}p+^{-1}_{0}\beta+\nu \end{equation} Thorium-234 decays by beta emission to Protactinium-234, according to the nuclear equation: \begin{equation} ^{234}_{90}Th\rightarrow ^{234}_{91}Pa + ^{-1}_{0}\beta + \nu \end{equation}