* Charge: The total charge of the reactants must equal the total charge of the products.

* Mass-energy: This is a bit more complex than just "mass". According to Einstein's famous equation E=mc², mass and energy are interchangeable. So, while the mass might not be exactly the same before and after the reaction, the total mass-energy will be conserved.

* Momentum: The total momentum of the system (including any emitted particles) must remain constant.

* Angular momentum: The total angular momentum (spin) of the system must also remain constant.

* Baryon number: The total number of baryons (protons and neutrons) must be conserved.

* Lepton number: The total number of leptons (electrons and neutrinos) must be conserved.

It's important to note that while the number of protons and neutrons individually might not be conserved, the *total* number of baryons (protons + neutrons) will always remain the same. The same principle applies to leptons.