**Isotopes:** Same $Z$, different $N$. Example: ${}^{12}\text{C}$ and ${}^{14}\text{C}$ (both $Z = 6$). - **Isotones:** Same $N$, different $Z$. Example: ${}^{13}\text{C}$ and ${}^{14}\text{N}$ (both $N = 7$). - **Isobars:** Same $A$, different $Z$. Example: ${}^{14}\text{C}$ and ${}^{14}\text{N}$ (