New results on element 109

铋-209

铋-209（209Bi）是铋的同位素之一，具有極微弱的放射性，半衰期長達1.9×1019年. 是鉍最穩定的同位素，也是所有發生α衰變的放射性同位素中已知半衰期最長的. 它有83個質子和126個中子，原子質量爲208.9803987原子質量單位.

Bismuth-209

Bismuth-209 (209Bi) is the isotope of bismuth with the longest known half-life of any radioisotope that undergoes α-decay (alpha decay).

Isotopes of meitnerium

Meitnerium (Mt) is an artificial element, and thus a standard atomic mass cannot be given.

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