CREATE TABLE table_15366768_1 (element VARCHAR2, isotopic_mass___u__ VARCHAR2)

What is the name of the element with isotopic mass of 158.925 34(2)?
SELECT element FROM table_15366768_1 WHERE isotopic_mass___u__ = "158.925 34(2)"
SELECT "element" FROM "table_15366768_1" WHERE "158.925 34(2)" = "isotopic_mass___u__"