Meitnerium

At a glance

Symbol

Mt

Atomic number

109

Mass number of its longest-lived isotope

[278]

Group

9

Period

7

Family

transition metal

Electron configuration

[Rn] 5f¹⁴ 6d⁷ 7s² (predicted)

Electronegativity

not measured

On the table

Period 7, group 9. The other transition metals are tinted, and every cell opens its own article.

Electrons and bonding

Only a handful of atoms have ever been made, each lasting seconds or less, so its chemistry is predicted from its place in the table rather than measured.

Properties

State at 25 °C

not known

Physical properties

none measured; no more than a few atoms have ever existed at once

Where it is found

Not found in nature. It is made a few atoms at a time in particle accelerators by fusing lighter nuclei, and each atom decays within seconds to hours.

Discovery and name

Armbruster and Münzenberg's team at GSI made a single atom of it in 1982 by fusing iron and bismuth nuclei. It was named after the Austrian-Swedish physicist Lise Meitner; with curium, it is one of only two elements that honor a woman.