043Transition metal · Group 7 · Period 5
Technetium
Technetium (Tc) is element 43, a transition metal in the d-block — group 7, period 5. It is a solid at room temperature with 5 electron shells (2, 8, 18, 13, 2) and an atomic mass of 98 u.
- Atomic mass
- 98.00 u
- Phase · STP
- solid
- Melting
- 2430 K · 2157 °C
- Boiling
- 4538 K · 4265 °C
- Electronegativity
- 1.9
- Density
- 11 g/cm³
Photograph — GFDL, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
Identity
- Atomic number
- 43
- Standard atomic weight
- 98.00 u
- Category
- Transition metal
- Group
- 7
- Period
- 5
- Block
- d-block
- Oxidation states
- +7, +6, +4
Physical properties
- Melting point
- 2430 K · 2157 °C
- Boiling point
- 4538 K · 4265 °C
- Density
- 11 g/cm³
- Molar heat capacity
- 24.27 J/(mol·K)
- Atomic radius
- 209 pm
- Electron affinity
- 53 kJ/mol
Atomic structure
43protons
55neutrons
43electrons
2valence e⁻
- Noble-gas notation
- [Kr] 4d5 5s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d5
- Electrons per shell
- 2, 8, 18, 13, 2
Periodic trends
Where Technetium ranks across all 118 elements.
Ionization energies
Energy to remove each successive electron (kJ/mol).
7021
1.5k2
2.9k3
Successive ionization energies (kJ/mol, log scale).
Discovery
- Discovered
- 1937
- Discovered by
- Emilio Segrè
- Named by
- —
- Appearance
- shiny gray metal