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105
Room of the Elements · No. 105

Dubnium (Db): what kind of element is it?

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In short

Dubnium is element number 105, with the symbol Db. Its name comes from the Russian city of Dubna.
Atomic number 105(268)
DbDubnium (dobuniumu)
Symbol
Db
Atomic weight
(268)
Place in the table
Period 7 · Group 5

The number in parentheses is not an atomic weight. It is the mass number of one radioactive isotope of the element.

Atomic weight from the Chemical Society of Japan, “Table of Standard Atomic Weights with Four Significant Figures (2026)”.

A Russian city’s name

The discovery of dubnium was reported in 1970 and 1971, and credit went to both the United States and the former Soviet Union. Its name was decided in 1997.

In the 1960s, the United States and the Soviet Union were racing to make new elements. It was hard to decide who had found each one first, so in 1986 an international working group was set up to re-examine the discoveries of elements 101 to 109.

In a 1994 proposal, “dubnium” was the name for element 104. In 1997 it was decided as the name for element 105.

Where it sits on the table

Dubnium is in the seventh row of Group 5, at the bottom of the column with vanadium, niobium and tantalum.

Think about it

There is no single right answer. Talking it over with someone at home is a good way to learn.

Did you know? — From the 1990s, a team from the United States and Russia worked together at Dubna and found the elements from 114 to 118.
Next steps
About this page
Symbol and atomic weight: Chemical Society of Japan, “Table of Standard Atomic Weights (2026)” and “Table of Atomic Weights with Four Significant Figures (2026)”. Origin of the name, year of discovery, year of naming and how it was made: Wakabayashi, “Chemistry of Superheavy Elements: The Birth of Nihonium Nh and Its Surroundings,” Kagaku to Kyōiku 65(3), 2017 (Chemical Society of Japan). All sources are in Japanese.
Written by CCN CO., LTD.
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