Atoms having different mass numbers but belonging to the same atomic chemical element and having the same atomic number are known as isotopes.
The examples are :
(i) Uranium : `text( )_92U^(234),text( )_92U^(235),text( )_92U^(238),`
(ii) Radium : `text( )_88Ra^(223),text( )_88Ra^(224),text( )_88Ra^(225),text( )_88Ra^(226),text( )_88Ra^(228)`
(iii) Thorium : `text( )_90Th^(227),text( )_90Th^(228),text( )_90Th^(229),text( )_90Th^(230),text( )_90Th^(231)`
Atoms having different mass numbers but belonging to the same atomic chemical element and having the same atomic number are known as isotopes.
The examples are :
(i) Uranium : `text( )_92U^(234),text( )_92U^(235),text( )_92U^(238),`
(ii) Radium : `text( )_88Ra^(223),text( )_88Ra^(224),text( )_88Ra^(225),text( )_88Ra^(226),text( )_88Ra^(228)`
(iii) Thorium : `text( )_90Th^(227),text( )_90Th^(228),text( )_90Th^(229),text( )_90Th^(230),text( )_90Th^(231)`