---
title: "Dubnium (Db) — element 105"
description: "Dubnium is element 105, symbol Db, most stable isotope 268. Configuration, properties, uses and neighbours."
url: https://atoneplace.net/element/dubnium/
site: "At One Place"
---

# Dubnium (Db)

**Dubnium — element 105: Db**

[268] · Transition metal · period 7, group 5

Dubnium is named after the Joint Institute for Nuclear Research at Dubna, north of Moscow, which is the only laboratory to have had a hand in discovering more than a handful of elements — Dubna's collaborations account for flerovium, moscovium, livermorium, tennessine and oganesson as well. The name was the compromise that ended the Transfermium Wars: Dubna gave up its claim to element 104, and got 105. Chemistry on a few atoms has confirmed it behaves as a group 5 element, though not quite as much like tantalum as simple extrapolation predicts.

## Properties

- **Atomic number:** 105
- **Symbol:** Db
- **Mass number of most stable isotope:** [268]
- **Category:** Transition metal
- **Group:** 5
- **Period:** 7
- **Block:** d-block
- **Electron configuration:** [Rn] 7s² 5f¹⁴ 6d³
- **Electrons per shell:** 2, 8, 18, 32, 32, 11, 2
- **Oxidation states:** +5, +4, +3
- **Discovered:** 1968 by Dubna, with independent work at Berkeley in 1970; IUPAC credited both

## Electron configuration

- **Full:** 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d³
- **Noble gas shorthand:** [Rn] 7s² 5f¹⁴ 6d³
- **Shells:** K: 2 · L: 8 · M: 18 · N: 32 · O: 32 · P: 11 · Q: 2

## What it is used for

- Research only; no application outside the laboratory

## Hazards

- Intensely radioactive; exists only as individual atoms in an accelerator

> Melting point, boiling point, density and electronegativity are omitted: no measurement is possible. The mass given is the mass number of dubnium-268, the longest-lived at roughly 28 hours.

> Several physical properties are not listed for dubnium because no bulk sample has ever existed. Only a handful of atoms have been produced, often with half-lives measured in seconds, so published melting points and densities for elements in this range are calculations rather than measurements. They are omitted rather than presented as observed values.

## Neighbours in the table

| Z | Element | Symbol | Mass |
| --- | --- | --- | --- |
| 103 | Lawrencium | Lr | [266] |
| 104 | Rutherfordium | Rf | [267] |
| 105 | Dubnium ← | Db | [268] |
| 106 | Seaborgium | Sg | [269] |
| 107 | Bohrium | Bh | [270] |

## Group 5

Elements in the same group share their outer electron count, which is why they behave similarly in reactions. Dubnium sits in group 5 with vanadium, niobium, tantalum.

## Common questions

### What is the atomic number of dubnium?

105. That is the number of protons in its nucleus, which is what defines the element.

### What is the symbol for dubnium?

Db.

### What is the electron configuration of dubnium?

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d³, or [Rn] 7s² 5f¹⁴ 6d³ in noble-gas shorthand.

## Related pages

- [Lawrencium (Lr)](https://atoneplace.net/element/lawrencium/)
- [Rutherfordium (Rf)](https://atoneplace.net/element/rutherfordium/)
- [Seaborgium (Sg)](https://atoneplace.net/element/seaborgium/)
- [Bohrium (Bh)](https://atoneplace.net/element/bohrium/)
- [Vanadium (V)](https://atoneplace.net/element/vanadium/)
- [Niobium (Nb)](https://atoneplace.net/element/niobium/)
- [Tantalum (Ta)](https://atoneplace.net/element/tantalum/)

## Sources

- Typical range compiled from manufacturer specifications — At One Place (/about/)