Nihonium ($Nh$)
The first element discovered in Asia—a superheavy synthetic metal born in the land of the rising sun, bridging the gap into the superheavy p-block.
Nihonium holds a special place in the history of science as the first chemical element to be discovered in Asia. It was synthesized by a team of Japanese scientists led by Kosuke Morita at the RIKEN Nishina Center for Accelerator-Based Science in Wako, Japan. Officially recognized in 2015, it was named Nihonium, derived from Nihon, one of the two ways to say "Japan" in Japanese, which translates to "the Land of the Rising Sun."
Occupying Group 13 in Period 7, Nihonium is a superheavy post-transition metal. It sits directly below Thallium. Like all superheavy elements, it is entirely synthetic and fiercely radioactive, existing only for fractions of a second before decaying into lighter elements.
Atomic & Radioactive Properties
Because its isotopes decay in milliseconds to seconds, bulk physical properties cannot be measured directly. Theoretical models predict it to be a dense, volatile metal.
| Property | Value |
|---|---|
| Atomic Number | 113 |
| Standard Atomic Weight | [286] |
| Electron Configuration | $[Rn] 5f^{14} 6d^{10} 7s^2 7p^1$ |
| Most Stable Isotope | 286Nh (Half-life: ~10 seconds) |
| Predicted Oxidation States | +1 (Most stable), +3 |
| Density (Predicted) | 16 g/cm³ |
Synthesis: The Long Quest at RIKEN
The Power of Patience
The RIKEN team utilized a "cold fusion" technique to create Nihonium. They fired a beam of Zinc-70 ions at a target made of Bismuth-209 moving at 10% the speed of light. The probability of these two nuclei fusing and surviving without immediately fissioning is astronomically low.
It took over nine years of continuous bombardment (from 2003 to 2012) for the team to definitively observe just three individual atoms of Nihonium. They proved their discovery by tracing the intricate alpha-decay chain down to the known isotope Mendelevium-254.
Group 13 Chemistry & Relativity
Nihonium is placed in Group 13 alongside Boron, Aluminum, Gallium, Indium, and Thallium. Based on classical trends, it should exhibit a $+3$ or $+1$ oxidation state. However, in the superheavy realm, relativistic effects drastically alter chemistry.
Due to the immense positive charge of its 113 protons, the $7s$ electrons travel at massive speeds, causing the $7s$ orbital to contract and stabilize deeply (the inert pair effect). Even more fascinating, the $7p$ orbital splits due to spin-orbit coupling. The single $7p_{1/2}$ electron in Nihonium is heavily stabilized.
As a result, theoretical calculations predict that Nihonium will strongly prefer the +1 oxidation state (like $NhOH$ or $NhCl$), acting somewhat similarly to Thallium, but possibly even less reactive, resembling the noble behavior of silver or gold.
This is the 113th part of our "Elements and Their Properties" series. We are deep into the superheavy p-block! To master the mathematics of spin-orbit coupling and relativistic orbital contraction, visit our Success Blueprint.
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