43 2 · 8 · 18 · 13 · 2

Technetium, Tc, element 43

Transition metal· Period 5· Group 7· d-block

Configuration [Kr]4d⁵5s²

Atomic weight: 97.9072Da
Phase: solid
Density: 11g/cm³
Melting point: 2,430.15K 2,157 °C
Boiling point: 4,535.15K 4,262 °C
Electronegativity: 2.1

Radioactive metallic transition element. Can be detected in some stars and the fission products of uranium. First made by Perrier and Segre by bombarding molybdenum with deutrons, giving them Tc-97. Tc-99 is the most stable isotope with a half-life of 2.6*10^6 years. Sixteen isotopes are known. Organic technetium compounds are used in bone imaging. Chemical properties are intermediate between rhenium and manganese. Description from mendeleev.

Back to the table

The outermost shell: the valence electronsThe inner shellsThe nucleus One bead for each electron, on the ring of its shell, counted from the nucleus out. The rings turn at their own pace; the model is Bohr's picture of the atom, which places electrons in shells but not on true orbits.

Atomic properties

5 of 5 fields have a value for technetium

Atomic weight The standard atomic weight. For an element with no stable isotope, the mass of its longest-lived isotope.: 97.90721Da; Source: mendeleev
Electron configuration: [Kr]4d⁵5s²; Source: mendeleev
Uncertainty of the atomic weight: 3×10⁻⁵Da; Source: mendeleev
Electron configuration in full The electron configuration with the noble-gas core written out.: 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d⁵5s²; Source: Worked outfrom electron configuration
Electrons in each shell Counted from the electron configuration, from the first shell outward.: 2 · 8 · 18 · 13 · 2; Source: Worked outfrom electron configuration

Screening of each subshell

Clementi's screening constants: how much of the nucleus's charge the other electrons hide from an electron in each subshell. What is left is the effective nuclear charge it feels.

Subshell	Screening σ	Effective charge Z − σ
1s	0.891	42.109
2s	11.3718	31.6282
2p	4.0592	38.9408
3s	16.2088	26.7912
3p	16.6159	26.3841
3d	14.647	28.353
4s	25.8016	17.1984
4p	27.1888	15.8112
4d	30.118	12.882
5s	35.7735	7.2265