The image shows a representative sample of 50 atoms of a fictious element, called lemonium ( Le ). Lemonium consists of three isotopes. The red spheres are Le – 19 , the light blue spheres are Le – 17 , and the dark blue spheres are Le – 15 . Determine the percent natural abundance of each of the three isotopes. pt. 2 Le –19 has an atomic mass of 19.0134 u, Le–17 has an atomic mass of 17.4629 u, and Le–15 has an atomic mass of 15.7384 u. Use the natural abundance and atomic mass of each isotope to determine the average atomic mass of Le.