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Nuclear Reactions

Nuclear Reactions

This lesson aligns with Next Generation Science Standards (NGSS) PS1.C

Nuclear reactions are processes in which one or two atomic nuclei and a subatomic particle collide with enough energy to produce one or more nuclides. Nuclear reactions involve the rearrangements of subatomic particles rather than atoms. They are used to measure the properties of nuclei. A nuclear reaction is simply a process that directly affects the nucleus of an atom. The nuclear reaction is quite different than the chemical reaction, which has nothing to do with the nucleus of an atom. In this article, we will learn about nuclear reactions, nuclear equations, energy conservation, types of nuclear reactions, etc.

Nuclear Reactions
A typical nuclear reaction involves two reacting particles; one is a heavy target nucleus and the other is a subatomic particle. It can be referred to as a process in which one or more atomic nuclides are produced from the collision of atomic nuclei or one atomic nucleus and a subatomic particle. The bombarding particle may either be an alpha particle, a neutron, a gamma-ray photon, a proton, or a heavy ion. However, the subatomic particle must have enough energy to approach the positively charged nucleus of an atom.

The reactants in a nuclear reaction are commonly known as parent nuclei, and the nuclides produced during a nuclear reaction are commonly referred to as daughter nuclei. The daughter nuclei are different than the parent nuclei. For example, the following image is a symbolic representation of a nuclear reaction!

In this reaction, Lithium-6 (36Li) and Deuterium (12H) both collide with each other with enough energy to produce the highly exciting nucleus of Beryllium-8 (48Be). Beryllium-8 further decays into two alpha particles of helium-4 (24He). Red spheres indicate the protons, while the blue spheres represent the neutrons.

Nuclear Equation 
A balanced chemical equation indicates that during a chemical reaction, bonds break and form, and atoms are rearranged, but the total number of atoms of each element remains the same. A nuclear equation reflects the fact that during a nuclear reaction, subatomic particles are rearranged instead of atoms. they also follow conservation laws and can be balanced in two ways.
  • The sum of the mass number of the reactants always equals the mass number of the products.
  • The sum of the charges of the reactants equals the sum of the charges of the products.
For example:
[math]36Li + 12H rarr 24He + ?[/math]

According to the balancing rules, the second nucleus must have atomic number 2 and mass number 4. Therefore, the balanced nuclear equation produced two alpha particles of helium-4. The complete nuclear equation is read as:
[math]36Li + 12H rarr 24He + 24He[/math]

Energy conservation
In a nuclear reaction, the total energy remains conserved. The energy released in a nuclear reaction can reappear in one of these ways. 
  • the kinetic energy of the daughter nuclei. 
  • emission of gamma rays.
The amount of energy released during a nuclear reaction can be determined by using Einstein’s mass-energy formula [math]E = mc^2[/math].

Types of Nuclear Reactions
There are two types of nuclear reactions that include nuclear fission and nuclear fusion.

Nuclear Fission
The nuclear fission reaction refers to the splitting of an atomic nucleus into two smaller nuclei. It can be defined as a process in which an atomic nucleus is bombarded with low-energy neutrons splitting the nucleus into smaller nuclei. Nuclear fission reactions release an abundant amount of energy, along with the emission of neutrons and gamma rays. 

The splitting of Uranium-235 is an important example of the nuclear fission reaction. The following equation is a complete description of this reaction.
[math]92235U + 01n rarr 56144Ba + 3689Kr + 301n[/math]

Nuclear Fusion 
In a nuclear fusion reaction, at least two atomic nuclei are fused to form a single nucleus. Subatomic particles such as protons and neutrons are also formed in such reactions. The fusion of deuterium (12H) and tritium (13H) has been illustrated in the following figure.

In this reaction, a helium (24He) atom and a neutron (01n) are formed as a product. Typically, such fusion reactions take place at the core of the sun and other stars. Nuclear fusion reactions end up losing mass and giving out a significant amount of energy. 

  • Nuclear reactions refer to the processes in which one or more atomic nuclides are produced from the collision between two atomic nuclei, one atomic nucleus, and a subatomic particle.
  • These reactions release a tremendous amount of energy which can be determined by Einstein’s formula [math]E=mc^2[/math].
  • Nuclear fission and nuclear fusion reactions are two common types of nuclear reactions.
  • Nuclear fission is the splitting of an atomic nucleus by the bombardment of neutrons into smaller nuclei.
  • A nuclear fusion reaction is a process in which at least two atomic nuclei come close together and fuse to form a single nucleus. 

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