28.1 The Transition Elements

Transition Elements

Definition

Definition: Transition Element

d-block element which forms one or more stable ions with incomplete d orbitals.

Transition elements are found in the d-block of the Periodic Table

Exceptions in the First Row (Period 4)

Scandium ()

• Forms only one stable ion, .
• Its electronic configuration is .
• Since the d-subshell is empty, it is not a transition element.

Zinc ()

• Forms only one stable ion, .
• Its electronic configuration is .
• Since the d-subshell is completely full it is not a transition element.

Electron Configuration

Anomalies in E.C.

1. Chromium (): instead of
2. Copper (): instead of

Recall: This happens because half-filled and fully-filled d-subshells offer extra thermodynamic stability.

E.C. of Ions

When forming positive ions, electrons in the subshell are always lost first, followed by the subshell.

Recall: The subshell is at a higher energy level.

Shape of d-orbitals

| |

The subscript denotes the plane of the orbital.

Lobes are along x and y axes.

Dumbbell shape with ring around centre.