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effects from closed nuclear shells is uncertain. It is not clear how many elements beyond the expected island of stability are physically possible, whether period 8 is complete, or if there is a period 9. The International Union of Pure and Applied Chemistry (IUPAC) defines an element to exist if its lifetime is longer than 10^-14 seconds (0.01 picoseconds, or 10 femtoseconds), which is the time it takes for the nucleus

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