Dubnium (Db)

Dubnium properties

Atomic number

105

Atomic mass

268 u

Category

Transition metal

Group

5

Period

7

Block

d-block

State at room temp.

Unknown

Electronegativity

—

Melting point

—

Boiling point

—

Density

—

Valence electrons

2

Common charges

+3, +4, +5

Oxidation states

+5, +4, +3

Atomic radius

—

Ionization energy

—

Electron affinity

—

Radioactive

Yes, no stable isotopes

Discovered

1967

Dubnium electron configuration

The electron configuration of Dubnium (Db) is [Rn] 5f14 6d3 7s2. Its 105 electrons are arranged in shells as 2, 8, 18, 32, 32, 11, 2.

Protons, neutrons and electrons in Dubnium

A neutral Dubnium atom has 105 protons and 105 electrons. Most Dubnium atoms have about 163 neutrons: the atomic mass rounded to 268, minus the atomic number 105.

Neutrons are approximate: atoms of the same element can have different numbers of neutrons (isotopes). Atomic number and mass

How many valence electrons does Dubnium have?

2

Dubnium has 2 valence electrons, counting the electrons in its outermost s subshell. Like most transition metals, it can also use d electrons in bonding.

See every element: Periodic table with valence electrons

Dubnium orbital diagram

Each box is an orbital that holds up to two electrons with opposite spins (↑↓). The inner shells are the same as the noble gas in brackets. How to write electron configurations

Molar mass of Dubnium

268 g/mol

One mole of Dubnium atoms (6.022 × 10²³ atoms) has a mass of 268 grams. Use this value to convert between grams and moles.

Dubnium facts

• Berkeley scientists proposed the name hahnium, after Otto Hahn, and that name appeared in many American books before dubnium was approved.
• Dubnium-268, which lasts for hours, was first seen at the end of the radioactive decay chain of moscovium.
• Dubnium (Db) has atomic number 105. It was discovered in 1967.

Position in the periodic table

Dubnium is element 105, in period 7 and group 5 of the periodic table, in the d-block.

All transition metals

Uses of Dubnium

Dubnium has no uses outside scientific research because it is made only a few atoms at a time. Some of its isotopes last for hours, which is long enough for chemists to study single atoms. These experiments compare dubnium with niobium and tantalum, the lighter elements in group 5, to see how relativistic effects alter its chemistry.

Who discovered Dubnium?

Georgy Flerov's team at Dubna in the Soviet Union first reported signs of dubnium in 1967 by bombarding americium with neon, and Albert Ghiorso's team at Berkeley reported it in 1970; credit is shared. It is named after Dubna, the Russian town that hosts the Joint Institute for Nuclear Research.

Where does the name come from?

Dubnium is named after Dubna, a town near Moscow, Russia, home of the Joint Institute for Nuclear Research, where some of the earliest work on this element was carried out.

Discovery timeline