Recognised as Chemical element
Technetium
- Tc
- Z = 43
- transition metal
- No stable isotope
Technetium (Tc) is element 43, a transition metal in period 5 and group 7. Its most stable isotope has mass number 98. Weights follow IUPAC standard atomic weights, 2021 revision.
Identity
SymbolTc
Mass number of the most stable isotope98this element has no stable isotope
Mass in kilograms1.6273283 × 10^-25
Categorytransition metal
Group7
Period5
Blockd-block
Electrons in a neutral atom43
Neutrons in the most common isotope55≈
Electron configuration
Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d⁵ 5s²ground state, subshells written in order of n
Noble gas shorthand[Kr] 4d⁵ 5s²
Electrons per shell2, 8, 18, 13, 2K, L, M and outward
Electrons in the outer shell2
Unpaired electrons5Hund's rule; unpaired electrons make the free atom paramagnetic
Madelung ruleFollowedthe ground state is what the n + l filling order predicts
Quantities
Molar mass98 g/mol
Mass of one mole98 grams
Atoms in one gram6.1450416 × 10^21
Mass of one atom1.6273283 × 10^-22 g
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