Niobium (Nb)
Niobium is element 41, a transition metal in group 5, period 5. A neutral atom has 41 protons, 52 neutrons and 41 electrons, 1 of them valence electrons.
Transition metal- Atomic number
- 41
- Atomic mass
- 92.906 u
- Valence electrons
- 1*
- Protons · neutrons
- 41 · 52
- Electrons per shell
- 2, 8, 18, 12, 1
- At room temperature
- solid
Bohr model of niobium
The Bohr model draws niobium as a nucleus of 41 protons and 52 neutrons, with its 41 electrons on 5 circular shells: 2 in shell 1, 8 in shell 2, 18 in shell 3, 12 in shell 4, 1 in shell 5. Press Build the atom to watch the shells fill from the inside out. The outer ring (the O 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 niobium
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹ 4d⁴
Short form (noble gas notation): [Kr] 5s¹ 4d⁴. The [Kr] stands for the electrons of krypton, the noble gas before it.
Niobium breaks the usual filling order. The Aufbau rule predicts 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d³, but experiments show the configuration above. The energy levels of the subshells are so close here that a different arrangement wins.
How many valence electrons does niobium have?
Niobium has 1 valence electron.
Niobium is a transition metal, so its valence electrons are less clear-cut than for main-group elements. It has 1 electron in its outermost shell (shell 5), and electrons in its inner d subshell can also take part in bonding.
Protons, neutrons and electrons
| Protons | 41 | equal to the atomic number |
|---|---|---|
| Electrons | 41 | equal to the protons in a neutral atom |
| Neutrons | 52 | mass number 93 − 41 protons |
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.
Niobium properties
| Symbol | Nb |
|---|---|
| Category | Transition metal |
| Group · period · block | 5 · 5 · d |
| Atomic mass | 92.906 u |
| State at 25 °C | solid |
| Melting point | 2,750 K (2,480 °C, 4,490 °F) |
| Boiling point | 5,017 K (4,740 °C, 8,570 °F) |
| Density | 8.57 g/cm³ |
| Electronegativity (Pauling) | 1.6 |
| Atomic radius | 207 pm |
| First ionization energy | 6.759 eV |
| Electron affinity | 0.893 eV |
| Oxidation states | +5, +3 |
| Common ion charge | +5, +3 |
| Discovered | 1801 by Charles Hatchett |
Where niobium sits on the periodic table
Group 5: Vanadium, Tantalum, Dubnium.
Questions about niobium
How many valence electrons does niobium have?
Niobium has 1 valence electron in its outer shell; inner d or f electrons can also bond.
How many protons, neutrons and electrons does niobium have?
A neutral niobium atom has 41 protons and 41 electrons. Its most common form has about 52 neutrons (mass number 93 − 41 protons).
What is the electron configuration of niobium?
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s¹ 4d⁴, written in short form as [Kr] 5s¹ 4d⁴.
What does the Bohr model of niobium look like?
A nucleus of 41 protons and 52 neutrons, circled by 5 electron shells holding 2, 8, 18, 12, 1 electrons.
What is the atomic number of niobium?
41. The atomic number is the number of protons in the nucleus, and it is what makes an atom niobium.