Nobelium

Named for Alfred Nobel, after a dispute over its discovery that took decades to settle.

At a glance

Symbol: No
Atomic number: 102
Mass number of its longest-lived isotope: [259]
Group: none; it sits in the actinide row below the table
Period: 7
Family: actinide
Electron configuration: [Rn] 5f¹⁴ 7s²
Electronegativity: 1.30
Common ions: No²⁺, unusually for an actinide, and No³⁺
Isotopes: none are stable; ²⁵⁹No lasts longest, about an hour

On the table

Period 7, in the actinide row set below the main table. The other actinides are tinted, and every cell opens its own article.

Electrons and bonding

Unlike most actinides, nobelium is most stable as No²⁺, because that ion keeps a completely filled set of fourteen 5f electrons.

Properties

State at 25 °C: solid
What it looks like: never made in visible amounts; expected to be a metal
Melting point: 827 °C (predicted)
Boiling point: not known
Density: not measured

Where it is found

Not found in nature; made a few atoms at a time in particle accelerators.

Discovery and name

A team at the Nobel Institute in Stockholm claimed it in 1957 and proposed the name nobelium, but the result could not be repeated. Work at Berkeley in 1958 and at Dubna in the Soviet Union in the 1960s followed. Credit eventually went to the Dubna team, but the name nobelium stayed.

What it is used for

Research only.

Handle with care

Radioactive; it has only ever existed a few atoms at a time.