Exercise Boron has two main isotopes: 10B and {}^11B Their atomic masses are 10.013 amu and 11.009 amu, respectively. Natural abundance of 10B is 19.90% What is the average atomic mass of Boron?Is it the same as the one on periodic table?

To find the average atomic mass of boron, we need to calculate the weighted average of the atomic masses of its isotopes based on their natural abundances.<br /><br />Given:<br />- Atomic mass of $10B$ = 10.013 amu<br />- Atomic mass of $11B$ = 11.009 amu<br />- Natural abundance of $10B$ = 19.90% (or 0.1990)<br />- Natural abundance of $11B$ = 100% - 19.90% = 80.10% (or 0.8010)<br /><br />The average atomic mass of boron can be calculated using the formula:<br /><br />Average atomic mass = (Atomic mass of $10B$ × Natural abundance of $10B$) + (Atomic mass of $11B$ × Natural abundance of $11B$)<br /><br />Plugging in the values:<br /><br />Average atomic mass = (10.013 amu × 0.1990) + (11.009 amu × 0.8010)<br /><br />Calculating the values:<br /><br />Average atomic mass = 1.9987 amu + 8.8089 amu<br /><br />Average atomic mass = 10.8076 amu<br /><br />Therefore, the average atomic mass of boron is approximately 10.8076 amu.<br /><br />The average atomic mass of boron calculated here is slightly different from the one on the periodic table, which is approximately 10.81 amu. This difference is due to rounding and the fact that the natural abundances of isotopes might not be exactly as stated in the question.