43TcTechnetium98[Kr] 4d⁵ 5s²
transition metal

Technetium

Technetium (/tɛkˈniːʃiəm/) is a chemical element with symbol Tc and atomic number 43. It is the element with the lowest atomic number in the periodic table that has no stable isotopes:every form of it is radioactive. Nearly all technetium is produced synthetically, and only minute amounts are found in nature.

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
4d5
5s2

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

Properties

At a glance

Atomic number
43
Atomic mass
98 u
Phase
Solid
Density
11 g/cm³
Melting point
2,430 K
Boiling point
4,538 K
First ionization energy
702 kJ/mol
Electronegativity
1.9
Electron affinity
53 kJ/mol
Molar heat capacity
24.27 J/(mol·K)
Period
5
Appearance
shiny gray metal

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

Keep exploring

Explore the stories, imagery, and reference data in more depth. Properties with no value in the reference are marked unavailable.