Chemical element whole number. For example, the relative atomic mass of chlorine is 35.453 u, which differs greatly from a whole number as it is an average of about 76% chlorine-35 and 24% chlorine-37. Whenever a relative atomic mass value differs by more than 1% from a whole number, it is due to this averaging effect, as significant amounts of more than one isotope are naturally present in a sample of that element. Chemists and nuclear scientists have different definitions of a "pure element". In chemistry, a pure element means a substance whose atoms all (or in practice almost all) have the
Westward the Course of Empire Takes Its Way imperial iconography and is regarded as a symbol of American exceptionalism and the realization of Manifest Destiny, ultimately leading to the evolution of the American Empire. The painting takes its inspiration from the closing lines of George Berkeley's "Verses on the Prospect of Planting Arts and Learning in America: <poem> Westward the course of empire takes its way; The first four Acts already past, A fifth shall close the Drama with the day; Time's noblest offspring is the last. </poem> The imagery of the pilgrim gesturing on a high rock is very similar to the 5 cent postage stamp, "Fremont