Technetium (Tc): electron configuration, atomic mass and facts
Technetium (Tc) is element 43 of the periodic table, a transition metal in period 5, group 7. Its electron configuration is [Kr] 4d5 5s2, with electrons arranged in shells 2, 8, 18, 13, 2, and its most stable isotope has mass number 98.
💡 The first element made artificially (1937).
▶ Watch Technetium’s electrons orbit in the interactive periodic tableTechnetium at a glance
| Symbol | Tc |
|---|---|
| Atomic number | 43 |
| Atomic mass | [98] u (most stable isotope) |
| Category | Transition metal |
| Group | 7 |
| Period | 5 |
| Block | d-block |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d5 5s2 |
| Noble-gas shorthand | [Kr] 4d5 5s2 |
| Electrons per shell | 2, 8, 18, 13, 2 |
| Electronegativity (Pauling) | 1.9 |
| State at 20 °C | solid |
Where is Technetium on the periodic table?
Technetium is in period 5, group 7, in the d-block. The period number matches its 5 electron shells, and the block names the subshell its last electrons fill. In the same group, Manganese sits directly above it and Rhenium sits directly below it. Elements in the same column of the d-block often have similar chemistry.
How to work out the electron configuration of Technetium
Put 43 electrons into subshells in order of rising energy, filling each before starting the next: 1s² (2), 2s² (4), 2p⁶ (10), 3s² (12), 3p⁶ (18), 4s² (20), 3d¹⁰ (30), 4p⁶ (36), 5s² (38), 4d⁵ (43). In shorthand, [Kr] stands for the 36 electrons of krypton, giving [Kr] 4d⁵ 5s².
How electronegative is Technetium?
Technetium has a Pauling electronegativity of 1.9, ranking 37 of the 100 elements with a known value (fluorine is highest at 3.98). That is in the middle of the range.
Frequently asked questions
What is the electron configuration of Technetium?
The electron configuration of Technetium (Tc) is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d5 5s2. In noble-gas shorthand it is written [Kr] 4d5 5s2.
How many electrons does Technetium have in each shell?
Technetium has 43 electrons arranged in shells as 2, 8, 18, 13, 2.
What is the atomic mass of Technetium?
Technetium has no stable isotopes. Its most stable isotope has a mass number of 98.
Is Technetium a metal?
Yes. Technetium is a transition metal.
Explore nearby elements
More transition metals: Zirconium, Niobium, Molybdenum, Ruthenium, Rhodium, Palladium. See all elements on the periodic table.