Technetium (Tc)
Technetium is element 43, a transition metal in period 5, group 7 of the periodic table. At room temperature it is a solid.
Electron configuration [Kr] 4d5 5s2
Electrons per shell 2, 8, 18, 13, 2
Technetium data
| Atomic number | 43 |
|---|---|
| Symbol | Tc |
| Atomic mass | [98] (mass number of the longest-lived isotope) |
| Category | Transition metal |
| Group | 7 |
| Period | 5 |
| Block | d |
| State at 25 °C | solid |
| Melting point | 2430 K (2156.9 °C) |
| Boiling point | 4538 K (4264.9 °C) |
| Density | 11.5 g/cm³ |
| Electronegativity (Pauling) | 1.9 |
| Atomic radius | 156 pm |
| 1st ionization energy | 702 kJ/mol |
| Electron affinity | -53 kJ/mol |
| Oxidation states | -3, -1, +1, +2, +3, +4, +5, +6, +7 |
| Common ion charge | 7+ |
| Discovered | 1937 |
Orbital diagram
Each box is one orbital holding up to two electrons of opposite spin. Following Hund’s rule, electrons spread out singly across a subshell before pairing.
Work through technetium’s configuration and its ions →
Where technetium sits
Technetium belongs to the transition metals. Its Pauling electronegativity of 1.9 is mid-range; see the electronegativity chart and periodic trends for context. To use its mass in a calculation, try the molar mass calculator.
Technetium FAQ
What is the electron configuration of technetium?
Technetium (Z = 43) has the configuration 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d5 5s2. In noble-gas shorthand that is [Kr] 4d5 5s2.
How many valence electrons does technetium have?
7 (2 outer s + 5 d electrons; 2 in the outermost shell).
What is the atomic mass of technetium?
Technetium has no stable isotopes. Its most stable known isotope has mass number 98, so tables list [98].
Is technetium a metal?
Yes. Technetium is a transition metal.
What is the charge of a technetium ion?
Technetium most commonly forms Tc7+.