Transition Metals and Electron Configuration

Classification of Elements

• Elements are classified into groups on the periodic table.
• Transition Metals: Special elements found in the d block of the periodic table.

Definitions of Transition Metals

General Definition

• Includes elements in Groups 3 through 12.
• These are considered transition metals because they are found in the d block.
• Involves understanding of electron configurations, specifically d orbitals.

IUPAC Definition

• IUPAC: International Union of Pure and Applied Chemistry.
• Defines a transition element as one whose atom has an incomplete d subshell.
• D Orbitals: Can hold a maximum of 10 electrons (5 orbitals x 2 electrons each).

Electron Configuration Examples

Iron (Fe)

• Electron configuration using noble gas notation:
  • Argon (Ar) in brackets, then 4s2 3d6 or 3d6 4s2.
• D Orbitals: 6 electrons = incomplete d subshell.
• Hence, iron is a transition metal per IUPAC definition.

Zinc (Zn)

• Electron configuration using noble gas notation:
  • Argon (Ar) in brackets, then 4s2 3d10 or 3d10 4s2.
• D Orbitals: 10 electrons = complete d subshell.
  • Does not meet the transition element definition.
• Zinc Ion (Zn²⁺)
  • Loses 2 electrons from 4s, resulting in 3d10.
  • Cation still has a complete d subshell.

Conclusion

• Two ways to think about transition metals:
  • General (Groups 3-12)
  • Specific (IUPAC definition)
• Important to be aware of both definitions for clarity in different contexts.