Assertion: uranium's isotope | /r/HasProperty | separated
Facets:
Source sentences:
text: Isotope separation is difficult because two isotopes of the same element have nearly identical chemical properties, and can only be separated gradually using small mass differences.
text: The difference in mass between U-235 and U-238 allows the isotopes to be separated and makes it possible to increase or "enrich" the percentage of U-235.