Silicon has three naturally occurring isotopes 9223 of28 Si

Silicon has three naturally occurring isotopes: 92.23% of^28 Si, with an atomic weight of 27.9769 amu; 4.68% of^29Si, with an atomic weight of 28.9765 amu; and 3.09% of^30Si, with an atomic weight of 29.9738 amu. On the basis of these data, confirm that the average atomic weight of Si is 28.0854 amu.

Solution

sol:

Si( 92.23%) atomic weight = 27.9769 amu

atomic weight = 27.9769*(92.23/100) = 25.803094

Si( 4.68%)atomic weight = 28.9765 amu

Atomic weight = 28.9765*(4.68/100) = 1.3561

Si(3.09% ) ofatomic weight = 29.9738 amu

Atomic weight = 29*9738*(3.09/100) = 0.92619

Average atomic weight = 25.803094+ 1.3561 + 0.92619

= 28.0854 amu