Question

Thallium consists of 29.5% TI-203 and 70.5% TI-205. Which is the relative atomic mass of thallium

Answer 1

Relative atomic mass for two isotopes can be calculated as follows

Isotope atomic mass abundance
²⁰³Tl 203 29.5%
²⁰⁵Tl 205 70.5%

Relative atomic mass
= (mass of 1 isotope x % abundance) + (mass of 2 isotope x % abundance)
= (203 x
`(29.5)/(100)`) + (205 x
`(70.5)/(100)`)
= 204.41 amu

Hence, relative atomic mass of Tl is 204.41amu