Write orbital diagrams for each ion and determine if the ion is diamagnetic or paramagnetic. a. N2+ b. V2+ c. Pd2+ d. Ru?
The Correct Answer and Explanation is:
Here are the orbital diagrams and magnetic properties for each ion.
a. Niobium(V) ion, Nb⁵⁺
- Electron Configuration: The neutral Niobium atom (Nb, atomic number 41) has the electron configuration [Kr] 5s¹ 4d⁴. To form the Nb⁵⁺ ion, five electrons are removed. These are the one 5s electron and the four 4d electrons. This leaves the electron configuration of the noble gas Krypton, [Kr].
- Orbital Diagram: The electron configuration [Kr] or [Ar] 3d¹⁰ 4s² 4p⁶ means all orbitals in the n=1, 2, 3, and 4 shells are completely filled. For the outermost shell (n=4):
- 4s: [↑↓]
- 4p: [↑↓] [↑↓] [↑↓]
- Magnetic Property: Since all electrons are paired, Nb⁵⁺ is diamagnetic.
b. Vanadium(II) ion, V²⁺
- Electron Configuration: The neutral Vanadium atom (V, atomic number 23) has the electron configuration [Ar] 4s² 3d³. To form the V²⁺ ion, two electrons are removed from the outermost shell, which is the 4s orbital. The resulting configuration is [Ar] 3d³.
- Orbital Diagram (for 3d electrons): According to Hund’s rule, electrons will occupy separate orbitals before pairing up.
- 3d: [↑] [↑] [↑] [ ] [ ]
- Magnetic Property: The ion has three unpaired electrons, making V²⁺ paramagnetic.
c. Palladium(II) ion, Pd²⁺
- Electron Configuration: The neutral Palladium atom (Pd, atomic number 46) has an exceptional electron configuration of [Kr] 4d¹⁰. To form the Pd²⁺ ion, two electrons are removed from the 4d orbital, resulting in the configuration [Kr] 4d⁸.
- Orbital Diagram (for 4d electrons): The eight electrons fill the five d-orbitals.
- 4d: [↑↓] [↑↓] [↑↓] [↑] [↑]
- Magnetic Property: The ion has two unpaired electrons, which means Pd²⁺ is paramagnetic.
d. Ruthenium(III) ion, Ru³⁺
- Electron Configuration: The neutral Ruthenium atom (Ru, atomic number 44) has an exceptional electron configuration of [Kr] 5s¹ 4d⁷. To form the Ru³⁺ ion, three electrons are removed: the one 5s electron first, followed by two 4d electrons. This leaves a configuration of [Kr] 4d⁵.
- Orbital Diagram (for 4d electrons): A half-filled d-subshell has one electron in each orbital.
- 4d: [↑] [↑] [↑] [↑] [↑]
- Magnetic Property: The ion has five unpaired electrons, so Ru³⁺ is paramagnetic.
Explanation
To determine if an ion is paramagnetic or diamagnetic, we must first find its electron configuration and create an orbital diagram for its valence electrons. Paramagnetic species possess one or more unpaired electrons and are attracted to an external magnetic field. Diamagnetic species have all their electrons paired and are weakly repelled by a magnetic field.
For transition metal cations, electrons are first removed from the s-orbital of the highest principal quantum number (n), and then from the (n-1)d orbital.
The Niobium(V) ion, Nb⁵⁺, is formed from a neutral Nb atom ([Kr] 5s¹ 4d⁴) by removing all five of its valence electrons. This results in the stable electron configuration of Krypton ([Kr]), where all electron orbitals are completely filled. With no unpaired electrons, Nb⁵⁺ is diamagnetic.
The Vanadium(II) ion, V²⁺, is formed from a neutral V atom ([Ar] 4s² 3d³) by removing the two 4s electrons. This leaves a configuration of [Ar] 3d³. The orbital diagram for the 3d subshell shows three unpaired electrons, each in a separate orbital as dictated by Hund’s rule. Therefore, V²⁺ is paramagnetic.
The Palladium(II) ion, Pd²⁺, originates from a neutral Pd atom, which has an exceptional configuration of [Kr] 4d¹⁰. Removing two electrons gives the ion a [Kr] 4d⁸ configuration. Its orbital diagram shows three filled d-orbitals and two d-orbitals with a single, unpaired electron each. The presence of these two unpaired electrons makes Pd²⁺ paramagnetic.
Finally, the Ruthenium(III) ion, Ru³⁺, comes from a neutral Ru atom ([Kr] 5s¹ 4d⁷). Removing three electrons (one from 5s, two from 4d) yields a [Kr] 4d⁵ configuration. This corresponds to a half-filled d-subshell, with five unpaired electrons. Consequently, Ru³⁺ is strongly paramagnetic.
