What is the electron configuration for the iridium (III) cation?:
The correct answer and explanation is:
The electron configuration for the iridium (III) cation (Ir³⁺) can be determined by first identifying the electron configuration of neutral iridium (Ir), and then adjusting for the removal of electrons due to the cation’s positive charge.
Step 1: Electron Configuration of Neutral Iridium (Ir)
Iridium (Ir) is a transition metal with an atomic number of 77. The electron configuration for a neutral iridium atom can be written as:
Ir: [Xe] 4f¹⁴ 5d⁷ 6s²
This means that the inner core electrons are represented by the xenon (Xe) configuration, and the remaining electrons are placed in the 4f, 5d, and 6s orbitals.
Step 2: Removal of Electrons for Iridium (III) Cation (Ir³⁺)
The iridium (III) cation has a 3+ charge, meaning it has lost three electrons. In transition metals, electrons are typically removed first from the outermost s-orbital, followed by the d-orbitals. Therefore, to form Ir³⁺, the electron configuration of neutral iridium must lose three electrons.
The two electrons are removed from the 6s orbital first, and then one electron is removed from the 5d orbital:
Ir³⁺: [Xe] 4f¹⁴ 5d⁶
Explanation:
Iridium (Ir) belongs to the transition metal series and has a relatively complex electron configuration due to its position on the periodic table. The removal of electrons from the 6s and 5d orbitals for the formation of the cation follows the general trend observed in transition metals where the s-orbitals are filled first and are also the first to be emptied when forming positive ions. This is due to the higher energy of the 6s orbital compared to the 5d orbitals in the case of iridium. As a result, the electron configuration for the Ir³⁺ ion is [Xe] 4f¹⁴ 5d⁶.