1. Conservation of Nucleon Number:
* The total number of protons and neutrons (nucleons) must remain the same before and after the reaction.
* This is reflected in the atomic mass number (A), which represents the total number of nucleons.
* Example: In the reaction ¹⁴N + ¹n → ¹⁴C + ¹H, the total number of nucleons is 15 on both sides.
2. Conservation of Charge:
* The total charge must be conserved.
* This means the sum of the atomic numbers (Z) of the reactants must equal the sum of the atomic numbers of the products.
* Example: In the reaction ⁴He + ¹⁴N → ¹⁷O + ¹H, the total charge is 8 on both sides.
3. Conservation of Energy:
* Energy cannot be created or destroyed, but it can be transformed from one form to another.
* This includes mass-energy equivalence, where mass can be converted into energy and vice versa.
* Example: Nuclear fission releases a huge amount of energy due to the conversion of a small amount of mass into energy.
4. Conservation of Linear Momentum:
* The total linear momentum of the system remains constant.
* This means the vector sum of the momenta of all particles involved before the reaction equals the vector sum of the momenta of all particles after the reaction.
* Example: In a nuclear reaction, the momentum of the incoming particle is transferred to the outgoing particles.
5. Conservation of Angular Momentum:
* The total angular momentum of the system remains constant.
* This includes the spin angular momentum of the particles involved.
* Example: The angular momentum of the nucleus can change during a nuclear reaction, but the total angular momentum of the system remains conserved.
6. Conservation of Lepton Number:
* Leptons (e.g., electrons, muons, neutrinos) are fundamental particles with half-integer spin.
* Lepton number is conserved separately for each lepton family (electron, muon, tau).
* Example: Beta decay involves the emission of an electron and an antineutrino, ensuring the electron lepton number remains constant.
These conservation laws are essential for understanding and predicting nuclear reactions. They form the basis of nuclear physics and have applications in areas such as nuclear power, medicine, and astrophysics.
