Question

Two isotopes of rubidium occur naturally, ${}_{37}{}^{85}Rb$and${}_{37}{}^{87}Rb$. Which isotope of rubidium is more abundant?

Short answer

The isotope of rubidium which is more abundant is${}_{37}{}^{85}Rb$.

Step-by-step solution

Given information

We need to find that out of ${}_{37}{}^{85}Rb$and ${}_{37}{}^{87}Rb$which is more abundant.

Explanation

The atomic mass of an element on the periodic table is used to find the most abundant isotope. The atomic mass of rubidium is $85.468amu$, as can be shown. Although no rubidium atom has that mass, it is the average mass of a rubidium sample.

When comparing the atomic masses of ${}_{37}{}^{85}Rb$and ${}_{37}{}^{87}Rb$, we can see that the atomic mass number on the periodic table is closer to that of ${}_{37}{}^{85}Rb$.

We can deduce that ${}_{37}{}^{85}Rb$is more plentiful.