Chemistry
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Dubnium is a chemical element in the periodic table with the atomic symbol Db and atomic number 105. This is a radioactive synthetic element whose most stable known isotope is 268Db with a half life of 28 hours (see below). Chemistry experiments have provided sufficient evidence to confidently place dubnium in group 5 of the Periodic Table.

Based on predicted location of nuclides which are stable against beta decay, maximum stability of Db isotopes should occur near 273Db. However, that Db isotope lies in a region where fission barriers are low. As a result, 268Db may actually be the most stable isotope of Db, known or unknown. A similar situation occurs with both At and Fr due to destabilization above N = 120.

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