Position in the Periodic Table
NCERT Reference:Chapter 4 – The d- and f-Block Elements – Page 105 (Part I)
Quick Notes
- d-block Elements (Transition Metals)
- Groups 3 to 12
- Filling of d-orbitals
- Show variable oxidation states, coloured compounds, catalytic activity
- Four series:
- 3d: Sc → Zn
- 4d: Y → Cd
- 5d: La, Hf → Hg
- 6d: Ac → Cn
- f-block Elements (Inner Transition Metals)
- Filling of 4f and 5f orbitals
- Placed separately at the bottom of the periodic table
- 4f (Ce–Lu): Lanthanides
- 5f (Th–Lr): Actinides
- IUPAC Definition
- Transition metals: Incomplete d-subshell in atom or ion
- Zn, Cd, Hg (group 12): Not transition metals (have full d10)
Full Notes
- d-block elements: Transition metals
- f-block elements: Inner transition metals
Series of Transition and Inner Transition Elements
Transition series (d-block):
- 3d series: Scandium (Sc) to Zinc (Zn)
- 4d series: Yttrium (Y) to Cadmium (Cd)
- 5d series: Lanthanum (La), Hafnium (Hf) to Mercury (Hg)
- 6d series: Actinium (Ac) and elements up to Copernicium (Cn)
Inner transition series (f-block):
- 4f series: Cerium (Ce) to Lutetium (Lu) – called Lanthanides
- 5f series: Thorium (Th) to Lawrencium (Lr) – called Actinides
Definition of Transition Elements (According to IUPAC)
Transition elements are metals with an incomplete d-subshell in either their neutral atoms or in any of their ions.
Elements with a completely filled d10 configuration in both ground and common oxidation states (like Zn, Cd, and Hg) are not considered transition metals.
Despite this, Zn, Cd, and Hg are often studied with transition metals due to similarities in chemical behavior.
Position in the periodic table
Summary
- d-block spans groups 3 to 12 with progressive filling of d-orbitals.
- f-block comprises lanthanides and actinides with filling of 4f and 5f orbitals.
- IUPAC defines transition metals by the presence of an incomplete d-subshell in atom or ion.
- Zn, Cd and Hg have d10 configurations and are not transition metals by definition.