Antimony has many uses, for example, in infrared devices and as part of an alloy in lead storage batteries. the element has two naturally occurring isotopes, one with mass 120.904 amu. the other with mass 122904 amu. (a) write the azx notation for each isotope, (b) use the atomic mass of antimony from the periodic table to calculate the natural abundance of each isotope.

Explanation:

(a). Isotopic symbols

The atomic number (Z) of antimony is 51. These isotopes have mass numbers (A) of 121 and 123.

The atomic number is a left subscript, and the mass number is a left superscript.

(b). Percent composition

The atomic mass of antimony is 121.760 u. 57.21

      Let x = the fraction of Sb-121

and 1 - x = the fraction of Sb-121. Then,

          120.904x + 122.904(1 - x) = 121.760

120.904x + 122.904 - 122.904x = 121.760

                    -2.000x + 122.904 = 121.760

                                     -2.000x = -1.144

                                                x = 0.5720

                                            1 - x = 1 - 0.5270 = 0.4280

Antimony is 57.20 % Sb-121 and 42.80 % Sb-123.