Nihonium

Nihonium is a synthetic chemical element with the symbol Nh and atomic number 113. It is extremely radioactive, with its most stable known isotope, nihonium-286, having a half-life of about 10 seconds. Nihonium is a transactinide element in the p-block of the periodic table, located in period 7 and group 13.

Nihonium was first reported to have been created in experiments in 2003 by a Russian–American team at the Joint Institute for Nuclear Research in Dubna, Russia. It was later confirmed by a Japanese team at Riken in Wakō, Japan in 2004. In 2015, the IUPAC/IUPAP Joint Working Party recognized the discovery and gave naming rights to the Riken team, who proposed the name nihonium in 2016, which was approved the same year. The name comes from the common Japanese name for Japan, Nihon.

Very little is known about nihonium because it has only been made in tiny amounts that decay quickly. It is expected to behave similarly to elements like boron, aluminium, gallium, indium, and thallium, but with some important differences. Early experiments suggest that nihonium is less reactive than thallium and not very volatile.

Introduction

Nihonium is a special element that scientists make in labs. Its symbol is Nh and its number is 113. This element is very unstable and breaks down fast — the longest-lasting version stays for about 10 seconds before changing. Nihonium is part of a group called transactinides, found on the outer part of the periodic table of elements.

History

The syntheses of elements were done at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, from 1981 to 1996. These elements were made by hitting targets of lead and bismuth with heavy ions. This made new nuclei and helped create superheavy elements.

The first report of element 113 was in August 2003. It was found as an alpha decay product of element 115. Element 115 was made by bombarding a target of americium-243 with calcium-48 projectiles. In 2004, these results were published.

A team of Japanese scientists at the Riken Nishina Center for Accelerator-Based Science in Wakō, Japan, led by Kōsuke Morita, also looked for element 113. In July 2004, they detected a single atom of 278113 and shared their results that September.

In December 2015, IUPAC published a report saying element 113 belonged to Riken. The full reports came out on 21 January 2016. IUPAC recognised Riken's discovery of element 113.

Before this, the element would have been called ununtrium (Uut), a systematic element name, until a name was chosen.

The Japanese team had thought of names like japonium, nishinanium, and rikenium. After IUPAC's decision, they chose the name nihonium, after Nihon, a Japanese name for Japan. In March 2016, Kōsuke Morita proposed "nihonium" to IUPAC, with the symbol Nh. The name was approved on 28 November 2016. The naming ceremony was held in Tokyo, Japan, on 14 March 2017, with Naruhito, then the Crown Prince of Japan, present.

Isotopes

Main article: Isotopes of nihonium

Nihonium does not happen in nature and has no stable forms. Scientists make different versions, called isotopes, of nihonium in labs. All these isotopes are radioactive and break down fast. The heaviest and most stable one, nihonium-286, lasts about 8 seconds before it changes.

Researchers have made eight isotopes of nihonium with different weights, but some of these have not been fully confirmed. Scientists are still studying these isotopes to learn more about their properties.

Predicted properties

Very few properties of nihonium or its compounds have been measured. This is because making and studying nihonium is very difficult and expensive, and it breaks down quickly. Most of what we know about nihonium is based on predictions.

Nihonium is the first element in the 7p series and the heaviest element in group 13 of the periodic table. It is found below boron, aluminium, gallium, indium, and thallium. All these elements except boron are metals, and nihonium is expected to be a metal too. Nihonium is predicted to behave differently from these lighter elements because of strong effects caused by how fast its electrons move, which is close to the speed of light.

Nihonium is expected to have an atomic radius about the same as thallium, but it should be much denser. It might melt at around 430°C and boil at around 1100°C. The chemistry of nihonium is expected to be different from thallium because of these strong effects, making nihonium less reactive.

Nihonium is predicted to prefer a +1 oxidation state, similar to thallium, but even more so. Simple compounds like nihonium monohydride (NhH) and monofluoride (NhF) are expected to exist. Nihonium might also show some properties similar to the halogens, like being able to gain an electron to form a -1 oxidation state. Higher oxidation states like +3 and +5 have been suggested for nihonium, but these compounds are expected to be very unstable.

Experimental chemistry

Scientists have studied nihonium to learn about its properties. They made nihonium atoms by mixing special materials and watched how the atoms moved through special tubes. They found that nihonium did not move easily, which surprised them.

In other tests, scientists looked at how nihonium sticks to different surfaces. They found that nihonium reacts a little less than a similar element but more than some nearby elements on the periodic table. This helps scientists understand nihonium better.