Is meitnerium a metal?

Meitnerium's chemical category has not been confirmed by experiment, so it is listed with unclassified properties.

How many protons does meitnerium have?

Meitnerium has 109 protons. Its atomic number is 109, which is also the number of electrons in a neutral atom of meitnerium.

What group and period is meitnerium in?

Meitnerium is in group 9 and period 7 of the periodic table, in the d-block.

What is the atomic mass of meitnerium?

The atomic mass of meitnerium is 278 u (unified atomic mass units).

Element 109

Meitnerium (Mt)

Element with unclassified properties · Period 7 · Group 9 · d-block

Meitnerium (Mt) is element 109 of the periodic table, an element with unclassified properties in period 7, group 9 (d-block) with an atomic mass of 278 and is a solid at standard conditions.

At a glance

Atomic number: 109
Symbol: Mt
Atomic mass: 278 u
Category: Unclassified properties
Period: 7
Group: 9
Block: d-block
Phase at STP: solid

Electron structure

Electron configuration: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 5f14 6d7 7s2
Shorthand configuration: [Rn] 5f14 6d7 7s2
Electrons per shell: 2, 8, 18, 32, 32, 15, 2
Oxidation states: +9

Physical properties

Meitnerium has only ever been produced in quantities too small to weigh or observe in bulk. The physical and atomic values below are theoretical predictions from periodic trends and relativistic calculations, not measurements.

Density: 37.4 g/cm³ (predicted)
Phase: solid

Atomic properties

Covalent radius: 129 pm (predicted)
First ionization energy: 800 kJ/mol (predicted)

Notable isotopes

Notable isotopes of Meitnerium: mass number, atomic mass, natural abundance, and stability.
Isotope	Mass	Abundance	Stability
Mt-278	278.15631	-	Half-life 4.5 seconds

Common uses

Scientific research only

Discovery

Year: 1982
Discovered by: Peter Armbruster, Gottfried Münzenberg
Country: Germany

Frequently asked questions

Is meitnerium a metal?: Meitnerium's chemical category has not been confirmed by experiment, so it is listed with unclassified properties.
How many protons does meitnerium have?: Meitnerium has 109 protons. Its atomic number is 109, which is also the number of electrons in a neutral atom of meitnerium.
What group and period is meitnerium in?: Meitnerium is in group 9 and period 7 of the periodic table, in the d-block.
What is the atomic mass of meitnerium?: The atomic mass of meitnerium is 278 u (unified atomic mass units).

Keep exploring

Meitnerium's row is on the printable element property sheet, and its tile is on the periodic table wall chart - the same numbers as above, laid out for A4 or A3 paper.