Complex sentence: Ununseptium may be located in the "island of stability", a concept in which some superheavy elements may be more stable than expected otherwise; the synthesized ununseptium atoms have lasted some tens and hundreds of microseconds.
Split into simpler sentences: Ununseptium may be located in the "island of stability", a concept that explains why some superheavy elements are more stable than expected. The synthesized ununseptium atoms have lasted some tens and hundreds of microseconds.