Nobelium

no group (f-block) · period 7 · f-block · actinide

Identity

Name and symbol: Nobelium, No
Atomic number: 102 protons
Position: no group (f-block) · period 7 · f-block · actinide
CAS number: 10028-14-5

Atomic structure

Atomic mass: 259 u
Electron configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴
[Rn] 7s²⁵f¹⁴
Electrons per shell: 2, 8, 18, 32, 32, 8, 2
Valence electrons: 16 ns, (n-1)d and (n-2)f

nuclide	half-life	decay
²⁶¹No	3 h [Estimated]	α ?
²⁵⁹No	58 m	α=75±0.4%; ε=25±0.4%; SF<10%
²⁶³No	20 m [Estimated]	α ?; SF ?
²⁵⁵No	3.52 m	β+=70±0.5%; α=30±0.5%

no stable isotope; the longest-lived nuclides

Physical properties

State at room temperature: Solid
Melting point: 1,100 K (826.85 °C)
Boiling point: not in sources
Density: not in sources
Appearance: not in sources
Thermal conductivity: not in sources
Electrical resistivity: not in sources
Electrical conductivity: not in sources
Crystal structure: face-centered cubic
Molar heat capacity: not in sources

Chemical properties

Oxidation states: +3, +2
Electronegativity: 1.3 (Pauling Scale)
Ionisation energy: 6.65 eV
1st 642 kJ/mol
Electron affinity: not in sources
Atomic radius: not in sources
Ionic radius: not in sources

Reactivity: Known only in aqueous tracer studies on thousands of atoms; the +2 state, with its filled 5f14 shell, is the stable one in solution, the only f-block element for which that is so, and No3+ is a good oxidant (E about +0.75 V for No3+ to No2+).
with water: Not known for the metal; in water without strong oxidants nobelium exists as No2+, which behaves like an alkaline-earth ion and elutes between Ca2+ and Sr2+.
with oxygen, air: Not known.
with acids: In acid solution exists as No2+ unless a strong oxidant is present; it complexes chloride weakly, like barium.
with halogens: A 1967 gas-transport experiment showed that nobelium reacts with chlorine to a non-volatile chloride, but whether it was NoCl2 or NoCl3 could not be determined.

Typical compounds: not in sources

Occurrence, production and use

Crustal abundance: Not Applicable
Oceanic abundance: Not Applicable

Occurrence and sources

synthetic only curium bombarded with carbon in a cyclotron

Extraction, production: not in sources

Uses: Since only tiny amounts of nobelium have ever been produced, there are currently no uses for it outside of basic scientific research.

Safety, toxicity: not in sources

Discovery and name

Discovered by: Joint Institute for Nuclear Research
Discovered: 1965
First isolated: not in sources
Named by: not in sources
Origin of the name: after Alfred Nobel

Nobelium does not occur naturally in the Earth’s crust. It was first synthesized in 1966 by Russian scientists from the Joint Institute for Nuclear Research (JINR) in Dubna, Russia under Georgi Flerov. Earlier claims to have synthesized “nobelium” beginning in 1957 were shown to be erroneous. This element was originally named for Alfred Nobel (Fig. IUPAC.102.1), the inventor of dynamite and founder of the Nobel prizes. The name was later retained because of its widespread use throughout the scientific literature [636], [638]. There are no uses for isotopes of nobelium outside of scientific research.

Nobelium is named after Alfred Nobel.

Conventions

Valence electrons are counted by the usual convention: the outer shell for s- and p-block elements, ns and (n-1)d for the d-block, ns, (n-1)d and (n-2)f for the f-block. Lanthanides and actinides are placed in the f-block with no group number. Electrical conductivity is the reciprocal of the printed resistivity. Ionic radii are Shannon effective radii, six-coordinate unless noted. Where a field reads “not in sources” the value was not found; it is a gap, not a zero. Regulatory limits are the published values and change often, so check the standard in force at your site and the numbers written into your own permit before you design to them.

Data

Element records, isotopes, radii and the descriptive text come from PubChem (NCBI), the Los Alamos National Laboratory periodic table, IUPAC CIAAW and the IAEA Atomic Mass Data Center. Appearance, thermal conductivity, electrical resistivity, crystal structure, discovery and the origin of each name come from Wikipedia and Periodic-Table-JSON, used under CC BY-SA 4.0. Hazard classifications come from the ECHA C&L inventory via PubChem. Ionic radii follow R. D. Shannon (1976). The water chapters cite their own sources at the foot of each entry, and are written to the level of Snoeyink and Jenkins, Stumm and Morgan, MWH's Water Treatment and Metcalf and Eddy.