109
Mt
Meitnerium
278
Meitnerium (Mt)
Transition MetalGroup 9Period 7d-block-blockRadioactive
Meitnerium is a chemical element with symbol Mt and atomic number 109. It is an extremely radioactive synthetic element (an element not found in nature that can be created in a laboratory). The most stable known isotope, meitnerium-278, has a half-life of 7.6 seconds.
Latin name: Meitnerium
Atomic Number
109
Atomic Mass
278 g/mol
Phase (STP)
Solid (predicted)
Electron Config.
[Rn] 5f¹⁴ 6d⁷ 7s²
General
SymbolMt
Atomic Number109
Atomic Mass278 g/mol
CategoryTransition Metal
Group9
Period7
Blockd-block
Electron Configuration[Rn] 5f¹⁴ 6d⁷ 7s²
Valence Electrons9
Colourmetallic (predicted)
Physical Properties
Phase (STP)Solid (predicted)
Density35 (predicted)
Melting Point1100 (predicted)
Boiling PointUnknown
Atomic Properties
Atomic Radius235 pm
Oxidation States+9, +8, +6
Ion ChargeMt6+/Mt8+/Mt9+
Nuclear & Hazards
RadioactiveYes
Half-life7.6 seconds (Mt-278)
Abundance
In Earth's Crust0%
Discovery & History
Discovery Year1982
Discovered ByGesellschaft für Schwerionenforschung (GSI), Darmstadt
Country of DiscoveryGermany
Isotopes of Meitnerium
| Isotope | Abundance | Half-life | Decay |
|---|---|---|---|
| Mt-276 | — | ~0.72 seconds | α |
| Mt-278 | — | ~4.5 seconds | α |