Electronic Configurations Of Elements And The Periodic Table

To determine the number of unpaired electrons in the ion, let's first consider the electron configuration of a neutral manganese (Mn) atom.

Manganese (Mn) has an atomic number of 25, so the electron configuration of neutral Mn is:


When manganese forms a ion, it loses two electrons. These electrons are removed first from the 4s orbital because it is higher in energy than the 3d orbital.

So, the electron configuration of is:


The 3d subshell has 5 electrons in the case of , and since the 3d orbitals can hold a maximum of 10 electrons, the 5 electrons will occupy the 5 available d orbitals with each orbital having 1 electron (this is the maximum number of unpaired electrons).

Therefore, the number of unpaired electrons in is:

Answer: 5

The correct pair of electron affinity order is O < S, Cl > F.

Here's why:

• Electron Affinity: Electron affinity is the change in energy (in kJ/mol) of a neutral atom (in the gaseous phase) when an electron is added to the atom to form a negative ion. More negative values indicate a higher (more favorable) electron affinity.
• Oxygen vs. Sulfur: Generally, electron affinity becomes more negative as you move from left to right across a period in the periodic table. However, there are exceptions. Oxygen has a smaller (less negative) electron affinity than sulfur. This is because oxygen has a relatively small size, and adding an electron results in significant electron-electron repulsion in the compact 2p orbitals, making it less favorable than adding an electron to the larger sulfur atom. Sulfur has more space in its 3p orbitals, so the electron repulsion is less.
• Fluorine vs. Chlorine: Similar to oxygen, fluorine is a small atom, leading to relatively strong electron-electron repulsions when an electron is added to the 2p orbitals. Chlorine, being larger, experiences less electron repulsion in its 3p orbitals, so its electron affinity is more negative than fluorine.

Therefore, the correct electron affinity order is O < S and Cl > F.

Correct Answer: O < S, Cl > F