Nobelium

Nobelium is named after Alfred Nobel, the inventor of dynamite who founded the Nobel Prizes. Its discovery was disputed between teams in Stockholm, Dubna (USSR) and Berkeley for years. The modern consensus credits a Soviet team at Dubna in 1966, though earlier experiments in 1958 produced similar results.

• Atomic Number102102 protons, 102 electrons
• Atomic Mass259.10100 u102× heavier than hydrogen
• State at Room TempSolidSolid
• DensityNot measured
• Melting / Boiling826.9°C
• Discovered1957

What is Nobelium?

Nobelium has 102 protons. Its most stable isotope, No-259, has a half-life of 58 minutes. Nobelium is the only actinide that prefers the +2 oxidation state in solution (rather than +3), because a +2 state gives it a particularly stable electron configuration. Only nanogram amounts have ever been synthesised.

Fact Nobelium is element 102, symbol No. As an actinide, it is part of the f-block of the periodic table: one of 15 radioactive elements from actinium (89) to lawrencium (103). All actinides are radioactive; none has a stable isotope. They are produced in nuclear reactors and by decay of heavier elements, and their chemistry has been studied using only microgram or nanogram quantities.

Where you find Nobelium

On Earth

Nobelium does not occur in significant natural abundance. It is produced only artificially, by bombarding heavier actinide targets with neutrons or lighter ions in nuclear reactors or particle accelerators. World production is measured in nanograms or picograms, a few billion atoms at most per year.

How we use Nobelium

At element 102, practical applications are limited by the extreme difficulty of production and the intense radioactivity. Nobelium has 102 protons

How it was discovered

Nobelium has 102 protons. Its most stable isotope, No-259, has a half-life of 58 minutes. Nobelium is the only actinide that prefers the +2 oxidation state in solution (rather than +3), because a +2 state gives it a particularly stable electron configuration. Only nanogram amounts have ever been synthesised.

Deeper dive: nobelium and the actinide series

The actinides (elements 89-103) form the lower of the two rows below the main body of the periodic table. They represent the filling of the 5f electron subshell. Unlike the lanthanides (the upper row), the actinides show greater variety in their chemistry because the 5f, 6d and 7s orbitals are close in energy. The early actinides, thorium through neptunium, can show many different oxidation states (e.g. uranium from +3 to +6). The heavier actinides increasingly resemble the lanthanides in preferring the +3 state.

All actinides beyond bismuth (83) are radioactive. The lightest, thorium, protactinium and uranium, have long enough half-lives to survive from the formation of the solar system. Neptunium and beyond are almost entirely synthetic, produced in nuclear reactors or accelerators. The transuranic elements were created at remarkable facilities including Oak Ridge National Laboratory, the Berkeley Cyclotron, the GSI in Darmstadt and JINR in Dubna.

Moving to 103 protons brings us to the next element on the periodic table.