Understanding Nihonium’s Atomic Structure
Nihonium (Nh) is a synthetic chemical element with atomic number 113. It is an extremely short-lived element, meaning it does not occur naturally on Earth and can only be created in laboratories through nuclear fusion reactions. Nihonium is named after “Nihon,” one of the two Japanese names for Japan, acknowledging the pioneering work of Japanese scientists at RIKEN who discovered it. As a superheavy element, its chemical properties are largely theoretical due to its extreme instability, with the longest-lived isotope having a half-life of only about 10 seconds.
Fundamental Particles in a Nihonium Atom
The atomic number (Z) of Nihonium is 113. This number defines the element and directly indicates the number of protons in the nucleus. For a neutral atom, the number of electrons is equal to the number of protons.
- Number of Protons: 113
- Number of Electrons: 113 (in a neutral atom)
To determine the number of neutrons, the mass number (A) of a specific isotope is required. The most stable known isotope of Nihonium is Nihonium-286 ($^{286}$Nh). The mass number represents the total count of protons and neutrons in the nucleus.
- Mass Number (A) for $^{286}$Nh: 286
- Number of Neutrons: Mass Number - Atomic Number = A - Z = 286 - 113 = 173
Therefore, a neutral atom of Nihonium-286 contains 113 protons, 113 electrons, and 173 neutrons.
Electron Configuration
The electron configuration describes how electrons are distributed in the atomic orbitals. For superheavy elements like Nihonium, the electron configuration can be predicted based on the Aufbau principle and Hund’s rule, although relativistic effects become significant and can slightly alter the expected order.
The predicted ground state electron configuration for Nihonium (Z=113) can be written using noble gas notation to simplify the representation, starting from the nearest noble gas, Radon (Rn), which has 86 electrons.
Full Electron Configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s² 5f¹⁴ 6d¹⁰ 7p³
Noble Gas Notation: [Rn] 5f¹⁴ 6d¹⁰ 7s² 7p³
This configuration shows that after filling the orbitals up to Radon, the electrons occupy the 5f, 6d, 7s, and 7p subshells. Specifically, there are 14 electrons in the 5f subshell, 10 electrons in the 6d subshell, 2 electrons in the 7s subshell, and 3 electrons in the 7p subshell.
Valence Electrons
Valence electrons are the electrons located in the outermost electron shell of an atom. These are the electrons that primarily determine an element’s chemical properties and its ability to form chemical bonds.
For Nihonium, the outermost shell is the seventh shell (n=7). The electrons in this shell are found in the 7s and 7p subshells.
- Electrons in 7s subshell: 2
- Electrons in 7p subshell: 3
The total number of valence electrons is the sum of electrons in these outermost subshells.
Total Valence Electrons: 2 (from 7s) + 3 (from 7p) = 5
This places Nihonium in Group 13 of the periodic table, alongside elements like Boron, Aluminium, and Indium, which also possess three valence electrons in their respective p-subshells and two in their s-subshells of the outermost energy level, giving them a total of five electrons in the outermost shell including those in the s and p subshell. While it is formally placed in Group 13, its expected chemistry, given its extreme mass and relativistic effects, may differ from its lighter congeners.