Transition Metals
Understanding the role of d-electrons in metallic bonding.
Delocalized d-electrons
For s-block metals, only the s-electrons are delocalized. Transition metals can delocalize electrons from both their 4s and 3d subshells, resulting in significantly more delocalized electrons holding the lattice together.
Case Study: Calcium vs Scandium
Calcium (Group 2)
- Config: [Ar] 4s²
- Delocalized: 2 electrons (4s only)
- Melting Point: ~842°C
Scandium (Transition)
- Config: [Ar] 3d¹ 4s²
- Delocalized: 3 electrons (4s + 3d)
- Melting Point: ~1541°C
The involvement of the 3d electron nearly doubles the melting point.
Conductivity Nuance
While transition metals are excellent conductors, more delocalized electrons doesn't always mean better conductivity. Silver and Copper are the best conductors, but Iron (with many d-electrons) is relatively resistive due to d-electron scattering effects. For exams, simply state they are "good conductors due to delocalized electrons."
Think About It
Tungsten (W) has the highest melting point of any metal (3422°C). It has the electron configuration [Xe] 4f¹⁴ 5d⁴ 6s². How does its electron configuration explain this extreme melting point?
Tungsten can delocalize up to 6 electrons (6s² + 5d⁴) into the metallic sea. Combined with a relatively small atomic radius for a Period 6 element (due to the lanthanide contraction from the filled 4f subshell), this creates an exceptionally high charge density and very strong metallic bonding.