Explain isotopes,isobars,isotones,and isomers by giving examples.

(N/A) Isotopes: Atoms having the same atomic number $Z$ but different mass numbers $A$ are called isotopes. Example: Hydrogen isotopes are ${ }_{1}^{1}H, { }_{1}^{2}H, { }_{1}^{3}H$. They have identical chemical properties.
Isobars: Atoms having the same mass number $A$ but different atomic numbers $Z$ are called isobars. Example: ${ }_{18}^{40}Ar$ and ${ }_{20}^{40}Ca$ are isobars.
Isotones: Atoms having the same number of neutrons $(N = A - Z)$ are called isotones. Example: ${ }_{6}^{14}C$ $(N=8)$ and ${ }_{8}^{16}O$ $(N=8)$ are isotones.
Isomers: Nuclei with the same atomic number $Z$ and same mass number $A$ but existing in different energy states are called nuclear isomers. Example: ${ }_{35}^{80}Br$ has a ground state and an excited state (metastable state denoted as ${ }_{35}^{80m}Br$).