Find three examples of ions in the periodic table that have an electron configuration of \(n d^{8}(n=3,4,5 \ldots) .\)

In order to solve this exercise, we need to recall the structure of the periodic table, and the rules for writing electron configurations. The periodic table is divided into groups (columns) and periods (rows). The elements in the same group have the same number of valence electrons. The electron configuration determines the distribution of electrons in the atomic orbitals. The electron configuration follows Aufbau principle, Hund's rule and Pauli's exclusion principle, and can be written in the form of \(\text{Principal Quantum Number} (\text{Orbital})^{\text{Number of Electrons}}\), such as "1s²2s²2p²".

Now we need to find the elements with electron configurations of \(n d^{8}(n=3,4,5 \ldots)\). In general, these configurations are common in the transition metals which are located in the d-block of the periodic table.

To obtain ions with given electron configurations, we need to focus on comparing the general electron configuration of their neutral state and the following given configurations: 1. \(3 d^{8}\) 2. \(4 d^{8}\) 3. \(5 d^{8}\) As our first example, consider the neutral palladium (Pd) atom, which has an electron configuration of [Kr] \(4 d^{10} 5 s^0\). If we remove two electrons from the 4d orbital, we get the \(Pd^{2+}\) ion with an electron configuration of [Kr] \(4 d^8\). For the second example, let's look at the neutral platinum (Pt) atom. It has an electron configuration of [Xe] \(4 f^{14} 5 d^{9} 6 s^1\). If we remove an electron from the 5d orbital and another from the 6s orbital, we get the \(Pt^{2+}\) ion with an electron configuration of [Xe] \(4 f^{14} 5 d^{8}\). For the third example, let's take the neutral iridium (Ir) atom. Its electron configuration is [Xe] \(4 f^{14} 5 d^{7} 6 s^2\). If we add an electron to the 5d orbital, we get the \(Ir^{-}\) ion with an electron configuration of [Xe] \(4 f^{14} 5 d^{8}\). These three ions are examples for the given electron configurations: \(Pd^{2+}\) with a \(4 d^8\) electron configuration, \(Pt^{2+}\) with a \(5 d^8\) electron configuration, and \(Ir^{-}\) with a \(5 d^8\) electron configuration.