41NbNiobium92.906372[Kr] 4d⁴ 5s¹
transition metal

Niobium

Niobium, formerly columbium, is a chemical element with symbol Nb (formerly Cb) and atomic number 41. It is a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite. The name comes from Greek mythology:Niobe, daughter of Tantalus since it is so similar to tantalum.

Electronic structure

A stylized shell model. Electrons are quantum objects, not particles following these literal paths. Sizes and motion are illustrative.

Electrons by shell
Electron configuration
4d4
5s1

36 is the [Kr] core total across four shells.

Properties

At a glance

Atomic number
41
Atomic mass
92.906372 u
Phase
Solid
Density
8.57 g/cm³
Melting point
2,750 K
Boiling point
5,017 K
First ionization energy
652.1 kJ/mol
Electronegativity
1.6
Electron affinity
88.516 kJ/mol
Molar heat capacity
24.6 J/(mol·K)
Period
5
Appearance
gray metallic, bluish when oxidized

Conditions and isotopes affect measured properties. Some properties of short-lived elements are predicted. Electronegativity uses the Pauling scale.

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