S'il existait un plus grand nombre d'éléments connus, il...

S'il existait un plus grand nombre d'éléments connus, il pourrait s'en trouver un en-dessous du polonium ( $Z=84)$ dans le tableau périodique. Quels seraient son numéro atomique et sa configuration électronique? Dans la même hypothèse, où se trouverait l'élément de numéro atomique $\mathrm{Z}=119$ ? Quelle serait sa configuration électronique?

S'il existait un plus grand nombre d'éléments connus, il pourrait s'en trouver un en-dessous du polonium ( $Z=84)$ dans le tableau périodique. Quels seraient son numéro atomique et sa configuration électronique?
Dans la même hypothèse, où se trouverait l'élément de numéro atomique $\mathrm{Z}=119$ ? Quelle serait sa configuration électronique?

Key Concepts

Electron Configuration

Electron configuration refers to the arrangement of electrons in the orbitals of an atom. It follows systematic rules such as filling lower-energy orbitals first (the aufbau principle), ensuring no two electrons share the same quantum number (the Pauli exclusion principle), and maximizing unpaired electrons in degenerate orbitals (Hund's rule). For hypothetical elements beyond those currently known, their electron configurations are extrapolated based on these filling rules, accounting for additional orbitals (and possibly new types of orbitals) that begin to be occupied.

Aufbau Principle

The aufbau principle is a guideline that electrons occupy orbitals starting from the lowest available energy levels and progressively filling higher levels. This rule is fundamental in predicting the order in which orbitals are occupied in both known and hypothetical elements. As the periodic table is extended, the aufbau sequence is used to determine how electrons would be arranged in new orbitals, leading to the prediction of electron configurations for elements that have not yet been observed.

Periodic Table Organization

The periodic table is arranged in rows (periods) and columns (groups) in order of increasing atomic number. Its structure reflects recurring chemical properties that are determined by the electron configurations of the elements. When considering hypothetical extensions of the table, one must preserve the periodic relationships by appropriately assigning new elements to positions based on their predicted electronic structures.

Atomic Number

The atomic number is the count of protons in an element’s nucleus and uniquely defines the chemical element. It also indicates how many electrons the neutral atom will have. In predicting new or hypothetical elements, determining the correct atomic number is essential as it governs the sequential buildup of electrons across available orbitals.

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