Beta Minus Decay
We want to determine what increases during decay of a radioactive element.
Step 1: Understanding Beta Minus Decay
In decay, a neutron within the nucleus is converted into a proton, an electron (the particle), and an antineutrino. The electron and antineutrino are emitted from the nucleus.
Step 2: Effects on Atomic Numbers
Mass Number (A): The mass number is the total number of protons and neutrons in the nucleus. Since a neutron is converted into a proton, the total number of nucleons (protons + neutrons) remains the same. The Mass number stays constant.
Atomic Number (Z): The atomic number is the number of protons in the nucleus. Since a neutron is converted into a proton, the atomic number increases by one.
Neutron Number (N): The number of neutrons decreases by one.
Step 3: Atomic Number and Proton Number
The atomic number is the same as the proton number. Therefore, during beta-minus decay, the proton number increases.
Conclusion
During decay of a radioactive element, there is an increase in its proton number (atomic number).