Question

There are two naturally occurring isotopes of thallium: ${}_{81}{}^{203}TI$and ${}_{81}{}^{205}TI$. Use the atomic mass of thallium listed on the periodic table to identify the more abundant isotope.

Short answer

${}_{81}{}^{205}TI$ is more abundant isotope of thallium.

Step-by-step solution

Given information.

We have been given that,

${}_{81}{}^{203}TI,{}_{81}{}^{205}TI$

We need to find which isotope is more abundant in nature.

Simplify.

${}_{81}{}^{205}TI$ is more abundant isotope of thallium as it comprises $70\%$atomic mass of thallium whereas ${}_{81}{}^{203}TI$isotope comprises only $30\%$of the atomic mass .