Nobelium
Definition and meaning of Nobelium in chemistry.
Nobelium is a synthetic radioactive element with the symbol No and atomic number 102. It is an extremely heavy actinide metal that is entirely artificially produced and is named in tribute to Alfred Nobel, the inventor of dynamite.
In more detail
Nobelium is painstakingly created in laboratories by bombarding curium or californium targets with carbon ions moving at significant fractions of the speed of light in a particle accelerator. Unlike most other actinides which overwhelmingly favor a +3 oxidation state, nobelium exhibits a highly stable +2 oxidation state in aqueous solution, behaving chemically more like an alkaline earth metal such as strontium. This distinctive chemical behavior is primarily attributed to the profound relativistic stabilization of its 5f electron shell, which firmly holds onto the f-electrons and prevents them from participating easily in chemical bonding. As an f-block element located late in the actinide series, its bulk physical properties are mostly inferred mathematically from its position in the periodic table rather than from any direct empirical measurement. The elemental metal has never been produced in macroscopic quantities, severely limiting comprehensive physical characterization.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | No |
| Atomic number | 102 |
| Atomic mass | [259] u |
| Category | Actinide |
| State at room temperature | Solid (predicted based on neighbors) |
| Year discovered | 1966 (confirmed by JINR) |
| Electron configuration | [Rn] 5f14 7s2 (predicted ground state) |
| Primary oxidation states | +2, +3 |
Nobelium isotopes are continuously studied in specialized particle physics laboratories to better understand the fundamental limits of nuclear stability and relativistic effects in superheavy elements.
Frequently asked questions
Why is the +2 oxidation state of nobelium so incredibly stable?
The +2 state is stable because losing two 7s electrons leaves a completely filled, relatively unreactive 5f subshell that is further stabilized by strong relativistic effects.
Was there any controversy surrounding the initial discovery of nobelium?
Yes, an international team originally claimed its discovery in 1957, but the claim was later retracted, and credit was ultimately awarded to Russian and American teams in the 1960s.