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Nuclear reactions involve changes in an atom's nucleus and can result in the transformation of elements. Unlike chemical reactions, where only electrons are involved, nuclear reactions impact the core of the atom, which holds protons and neutrons. These changes can lead to the creation of new elements or isotopes.
In the realm of nuclear reactions, there are two main types: fusion and fission. Another important subcategory includes radioactive decay, where unstable nuclei lose energy by emitting radiation. A common type of decay is \(\beta^-\) decay, where a neutron is converted into a proton, an electron (beta particle), and an electron antineutrino.
To write a nuclear reaction equation, one must balance the atomic and mass numbers on both sides. This ensures that the principle of conservation of both mass and charge is adhered to. For example, in the \(\beta^-\) decay of \(^{90}\mathrm{Sr}\) into \(^{90}\mathrm{Y}\), the mass number remains 90, but the atomic number increases by one as a neutron becomes a proton.

Radioisotopes are isotopes of elements that are unstable and exhibit radioactivity. This instability occurs because of an imbalance in the number of protons and neutrons in the atom's nucleus. As a result, radioisotopes tend to decay over time by emitting ionizing radiation in the form of alpha, beta, or gamma rays.
\(^{90}\mathrm{Sr}\) is a notable radioisotope. It is an isotope of strontium and often emerges as a by-product in nuclear reactors. Its chemical properties are similar to calcium, making it a concern for human health as it can accumulate in bones when ingested.
Radioisotopes have varying stability and half-lives, which is the time it takes for half of a sample to decay. This property makes them useful in various applications such as in medical diagnostics, treatment (like cancer radiotherapy), and even food preservation by irradiation.

• They help in radiometric dating to determine the age of materials.
• They serve as tracers in biological and chemical research.

Nuclear chemistry is the study of the chemical and physical properties of elements as influenced by nuclear and radioactive processes. This branch of chemistry plays a crucial role in discovering the applications and effects of radioactivity and isotopic change.
It encompasses the study of phenomena such as radioactive decay, fission, and fusion. In particular, the study of nuclear reactions like \(\beta^-\) decay is important in understanding how elements transform under certain conditions.
Beta decay is an integral concept in nuclear chemistry. Here, it's crucial to note that the element undergoing decay changes its atomic number but typically retains its mass number. This reaction reveals insights into the balance of forces within a nucleus and the conservation of certain properties like angular momentum.
Nuclear chemists use this knowledge to innovate and tackle challenges such as nuclear waste management, where understanding decay processes can help in devising methods to reduce environmental and biological impacts.

• They work on developing nuclear power sources that are safer and more efficient.
• Nuclear chemistry aids in medical advancements, particularly in the development of diagnostic tools and treatments using radioisotopes.