Original sentence: Chemical element masses, as expressed in u, would therefore all be close to whole number values (within 2% and usually within 1%) were it not for the fact that atomic weights of chemical elements are averaged values of the various stable isotope masses in the abundances which they naturally occur.For example, chlorine has an atomic weight of  because it is composed of 76%  () and 24%  ()
Edited sentence: Chemical element masses, as expressed in u, would therefore all be close to whole number values (within 2% and usually within 1%) were it not for the fact that atomic masses of chemical elements are averaged values of the various stable isotope masses in the abundances which they naturally occur.For example, chlorine has an atomic mass of  because it is composed of 76%  () and 24%  ()