Nobelium
Definition and meaning of Nobelium in chemistry.
![Nobelium element card: symbol No, atomic number 102, atomic mass [259], electron configuration [Rn] 5f¹⁴ 7s², oxidation states +3, Actinide, f-block, period 7, solid at room temperature.](/assets/images/terms/nobelium-chemical-element.webp)
Nobelium is a synthetic and highly radioactive chemical element with the symbol No. It has an atomic number of 102 and belongs to the heavy actinide series. Scientists named this completely artificial metal to honor Alfred Nobel, the inventor of dynamite.
In more detail
Researchers create nobelium in laboratories using large machines called particle accelerators. They take a target made of radioactive elements like curium or californium. Then, they bombard this target with carbon ions moving near the speed of light.
Nobelium behaves very differently from most other heavy elements in the actinide series. Most actinides strongly prefer a +3 oxidation state during their chemical reactions. An oxidation state describes the number of electrons an atom loses to form bonds.
In a water solution, nobelium strongly favors a very stable +2 oxidation state instead. It acts more like an alkaline earth metal, such as the element strontium. This strange behavior happens because of a strong effect called relativistic stabilization.
The atom holds its outermost electrons very tightly in its 5f electron shell. These trapped electrons cannot easily participate in forming chemical bonds with other atoms. Nobelium sits very late in the actinide series on the periodic table.
Scientists have never produced this elemental metal in amounts large enough to see. This severe limit prevents them from directly measuring its true physical characteristics. Instead, chemists must infer its bulk physical properties using complex math and periodic trends.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | No |
| Atomic number | 102 |
| Atomic mass | [259] u |
| Category | Actinide |
| Year discovered | 1966 (confirmed by JINR) |
| Primary oxidation states | +2, +3 |
Scientists constantly study nobelium isotopes in highly specialized particle physics laboratories around the world. These experiments help researchers understand the fundamental limits of nuclear stability in heavy elements. The data also reveal how fast-moving electrons change the chemistry of superheavy atoms.
Frequently asked questions
Why is the +2 oxidation state of nobelium so incredibly stable?
The +2 state is stable because the atom loses exactly two outer electrons. This leaves a completely filled 5f subshell that resists chemical reactions. Strong relativistic effects make this filled electron subshell even more stable.
Was there any controversy surrounding the initial discovery of nobelium?
Yes, an international team claimed they discovered the element first in 1957. They later retracted this claim due to incorrect and flawed experimental data. Scientists finally awarded official credit to Russian and American teams in the 1960s.
Related terms
Sources & references
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