Question

How many unpaired electrons are present in the tetrahedral ion \(\mathrm{FeCl}_{4}^{-} ?\)

Short answer

The \(\mathrm{FeCl}_{4}^{-}\) ion contains 3 unpaired electrons.

Step-by-step solution

Find the atomic number for Fe.

The atomic number can be found on the periodic table. It is the number associated with the chemical symbol for iron, which is Fe. According to the periodic table, the atomic number for Fe is 26.

Determine the number of electrons in Fe.

Iron in its elemental state should have as many electrons as its atomic number, which is 26. Iron (Fe) atoms in their ground (unexcited) state have 26 electrons.

Write the electronic configuration of neutral Fe.

The electronic configuration for iron (Fe) in the ground state can be written as follows: \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{6}\).

Write the electronic configuration of \(\mathrm{FeCl}_{4}^{-}\).

When Fe forms the \(\mathrm{FeCl}_{4}^{-}\) ion, it loses 3 electrons from the \(4s\) and \(3d\) shells. This results in 23 electrons, and their configuration can be written as: \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{3}\).

Calculate the number of unpaired electrons.

To determine the number of unpaired electrons, count the number of electrons in the d orbitals that are not paired. From the computed electronic configuration, there are 3 unpaired electrons in the d orbitals. So, the \(\mathrm{FeCl}_{4}^{-}\) ion contains 3 unpaired electrons.