Niobium (Nb)

Atomic Model Details

Niobium (Nb) is a transition metal with the following atomic characteristics:

Atomic Symbol: Nb
Atomic Number (Z): 41
Atomic Mass (Average): 92.906 g/mol
Number of Protons: 41
Number of Electrons (in a neutral atom): 41
Number of Neutrons (for Niobium-93, the most common isotope): 93 - 41 = 52
Atomic Radius (Metallic): 146 pm

Electronic Configuration & Shell Diagram

Electronic Configuration

The ground state electronic configuration of Niobium is: [ \text{[Kr]} , 4d^3 , 5s^2 ] Expanded form: [ 1s^2 , 2s^2 , 2p^6 , 3s^2 , 3p^6 , 3d^{10} , 4s^2 , 4p^6 , 4d^3 , 5s^2 ]

Shell Diagram Representation (Textual)

The distribution of electrons in different principal shells (K, L, M, N, O) for Niobium is as follows:

K-shell (n=1): 2 electrons ($1s^2$)
L-shell (n=2): 8 electrons ($2s^2 , 2p^6$)
M-shell (n=3): 18 electrons ($3s^2 , 3p^6 , 3d^{10}$)
N-shell (n=4): 11 electrons ($4s^2 , 4p^6 , 4d^3$)
O-shell (n=5): 2 electrons ($5s^2$)

This configuration reflects its position as a d-block element, where the differentiating electron enters the $(n-1)d$ subshell.

Periodic Trends

Niobium’s position in Period 5, Group 5 of the periodic table dictates its periodic properties:

First Ionization Enthalpy: 652.1 kJ/mol
- This is the energy required to remove the outermost electron from a gaseous niobium atom.
Electronegativity (Pauling Scale): 1.6
- Niobium has moderate electronegativity, characteristic of transition metals, indicating its tendency to attract electrons in a chemical bond.
Electron Gain Enthalpy: -89 kJ/mol
- This indicates that energy is released when an electron is added to a gaseous niobium atom, but it’s a relatively small value for a metal, reflecting its metallic character where losing electrons is more favourable.
Atomic Radius (Metallic): 146 pm
- As a transition metal, its atomic radius is larger than elements in earlier periods of the same group but generally decreases across a period due to increasing nuclear charge.

Key Physical Properties

Niobium is a refractory metal known for its distinctive physical attributes:

Density: 8.57 g/cm³ (at 20°C)
- It is a relatively dense metal.
State at 25°C: Solid
- Like all metals at room temperature (except Mercury).
Color: Lustrous grey metal
- Its metallic luster is characteristic of d-block elements.
Melting Point: 2477 °C (2750 K)
- Niobium has a very high melting point, classifying it as a refractory metal.
Boiling Point: 4744 °C (5017 K)
- It possesses an extremely high boiling point.