# How would you compare the abundance of the two naturally occurring isotopes of boron?

Jan 5, 2017

By the atomic mass quoted on the Periodic Table.......

#### Explanation:

The Periodic Table lists the atomic mass of boron as $10.81 \cdot g \cdot m o {l}^{-} 1$. This site informs me that the percentage occurrence of ""^(10)B is 19.9%, and of ""^(11)B, 80.1%.

These are the only significant isotopes of boron, and their weighted average is:

(10xx19.9%+11xx80.1%)*g*mol^-1 $=$ $10.81 \cdot g \cdot m o {l}^{-} 1$

And thus, when you look on your copy of the Periodic Table, you find this molar mass quoted.