Dubnium (Db)
Dubnium is element 105, a transition metal in group 5, period 7. A neutral atom has 105 protons, 163 neutrons and 105 electrons, 2 of them valence electrons.
Transition metal- Atomic number
- 105
- Atomic mass
- [268] u
- Valence electrons
- 2*
- Protons · neutrons
- 105 · 163
- Electrons per shell
- 2, 8, 18, 32, 32, 11, 2
- At room temperature
- —
Bohr model of dubnium
The Bohr model draws dubnium as a nucleus of 105 protons and 163 neutrons, with its 105 electrons on 7 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 32 in shell 4, 32 in shell 5, 11 in shell 6, 2 in shell 7. Press Build the atom to watch the shells fill from the inside out. The outer ring (the Q shell) is dashed: the electrons there are the ones that take part in chemistry.
Real electrons don't travel in neat circles. They live in fuzzy orbitals, shown below, but the Bohr picture is the quickest way to count shells and valence electrons.
Electron configuration of dubnium
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d³
Short form (noble gas notation): [Rn] 7s² 5f¹⁴ 6d³. The [Rn] stands for the electrons of radon, the noble gas before it.
How many valence electrons does dubnium have?
Dubnium has 2 valence electrons.
Dubnium is a transition metal, so its valence electrons are less clear-cut than for main-group elements. It has 2 electrons in its outermost shell (shell 7), and electrons in its inner d subshell can also take part in bonding.
Protons, neutrons and electrons
| Protons | 105 | equal to the atomic number |
|---|---|---|
| Electrons | 105 | equal to the protons in a neutral atom |
| Neutrons | 163 | mass number 268 − 105 protons (for its longest-lived isotope, Db-268) |
Atoms of the same element can have different numbers of neutrons (isotopes). The count above uses the rounded atomic mass, the way it's taught in class.
Dubnium properties
| Symbol | Db |
|---|---|
| Category | Transition metal |
| Group · period · block | 5 · 7 · d |
| Atomic mass | [268] u |
| State at 25 °C | solid |
| Melting point | — |
| Boiling point | — |
| Density | — |
| Electronegativity (Pauling) | — |
| Atomic radius | — |
| First ionization energy | — |
| Electron affinity | — |
| Oxidation states | 5, 4, 3 |
| Common ion charge | 5, 4 |
| Discovered | 1967 by Joint Institute for Nuclear Research |
Where dubnium sits on the periodic table
Group 5: Vanadium, Niobium, Tantalum.
Questions about dubnium
How many valence electrons does dubnium have?
Dubnium has 2 valence electrons in its outer shell; inner d or f electrons can also bond.
How many protons, neutrons and electrons does dubnium have?
A neutral dubnium atom has 105 protons and 105 electrons. Its most common form has about 163 neutrons (mass number 268 − 105 protons).
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, written in short form as [Rn] 7s² 5f¹⁴ 6d³.
What does the Bohr model of dubnium look like?
A nucleus of 105 protons and 163 neutrons, circled by 7 electron shells holding 2, 8, 18, 32, 32, 11, 2 electrons.
What is the atomic number of dubnium?
105. The atomic number is the number of protons in the nucleus, and it is what makes an atom dubnium.