Question

Why do transition elements (d-block) show variable oxidation states and magnetic properties?

Hint:

Greater the number of unpaired d-electrons, stronger is the paramagnetic behavior of a transition element.

Answer 1

Concept: Transition elements (d-block elements) have partially filled d-orbitals. Their electronic configuration allows flexibility in electron participation during bonding, leading to unique chemical and physical properties.
1. Variable Oxidation States: Reason:
The energy difference between \( ns \) and \( (n-1)d \) orbitals is very small.
Both types of electrons can participate in bond formation.
As a result, different numbers of electrons may be lost or shared.
Example:
Iron: \( +2 \) and \( +3 \)
Manganese: \( +2 \) to \( +7 \)
Thus, multiple oxidation states are observed.
2. Magnetic Properties: Reason:
Magnetic behavior depends on presence of unpaired electrons.
Partially filled d-orbitals often contain unpaired electrons.
Types of Magnetism:
Paramagnetism: Due to unpaired electrons (most transition metals)
Diamagnetism: When all electrons are paired
Ferromagnetism: Strong magnetic ordering (e.g., Fe, Co, Ni)

Summary:
Variable oxidation states arise from participation of both \( s \) and \( d \) electrons.
Magnetic properties arise from unpaired d-electrons.