Chemistry > d and f Block Elements > 7.0 Lanthanoid Series
d and f Block Elements
1.0 General Introduction and Electronic Configuration
2.0 Occurrence and General Characteristics of Transition Elements
3.0 General Trends in properties of First Row Elements
3.1 Ionisation Enthalpy
3.2 Oxidation State
3.3 Atomic and Ionic Radii
3.4 Colour
3.5 Catalytic properties
3.6 Magnetic Properties
3.7 Formation of Interstitial Compounds
3.8 Alloy Formation
4.0 Potassium dichromate
5.0 Potassium permanganate
5.1 Properties of potassium permanganate
5.2 Structure of manganate ion and permanganate ion
5.3 Disproportion of an oxidation state
5.4 Uses
6.0 F-Block Elements - Introduction
7.0 Lanthanoid Series
7.1 Position of Lanthanoid Series
7.2 Electronic configuration of lanthanoids
7.3 Oxidation States
7.4 Chemical Reactivity of Lanthanides
8.0 Lanthanoid Contraction and its consequence
9.0 Actinoids Series
9.1 Position of Actinoids in periodic table
9.2 Electronic Configuration of actinoids
9.3 Oxidation states of actinoids
10.0 Comparison between lanthanoids and actinoids
7.3 Oxidation States
3.2 Oxidation State
3.3 Atomic and Ionic Radii
3.4 Colour
3.5 Catalytic properties
3.6 Magnetic Properties
3.7 Formation of Interstitial Compounds
3.8 Alloy Formation
5.2 Structure of manganate ion and permanganate ion
5.3 Disproportion of an oxidation state
5.4 Uses
7.2 Electronic configuration of lanthanoids
7.3 Oxidation States
7.4 Chemical Reactivity of Lanthanides
9.2 Electronic Configuration of actinoids
9.3 Oxidation states of actinoids
- Total numerical charge assigned on the atom of an element in molecule is called oxidation state.
- Lanthanoids show $+3$ common oxidation state by losing two electrons from $6s$ and one from $5d$ or $4f$.
- In addition to $+3$ they may show $+2$ and $+4$ oxidation state.
| Element | Oxidation State | Outer electronic configuration of | |||
| $M$ | ${M^{ + 2}}$ | ${M^{ + 3}}$ | ${M^{ + 4}}$ | ||
| La | +3 | $5{d^1}6{s^2}$ | - | $5{d^0}6{s^0}$ | - |
| Ce | +3,+4 | $4{f^2}6{s^2}$ | - | $4{f^1}6{s^0}$ | $4{f^0}6{s^0}$ |
| Pr | +3,+4 | $4{f^3}6{s^2}$ | - | $4{f^2}6{s^0}$ | $4{f^1}6{s^0}$ |
| Nd | +2,+3,+4 | $4{f^4}6{s^2}$ | $4{f^4}6{s^0}$ | $4{f^3}6{s^0}$ | $4{f^2}6{s^0}$ |
| Pm | +3 | $4{f^5}6{s^2}$ | - | $4{f^4}6{s^0}$ | - |
| Sm | +2,+3 | $4{f^6}6{s^2}$ | $4{f^6}6{s^0}$ | $4{f^5}6{s^0}$ | - |
| Eu | +2,+3 | $4{f^7}6{s^2}$ | $4{f^7}6{s^0}$ | $4{f^6}6{s^0}$ | - |
| Gd | +3 | $4{f^7}5{d^1}6{s^2}$ | - | $4{f^7}6{s^0}$ | - |
| Tb | +3,+4 | $4{f^9}6{s^2}$ | - | $4{f^8}6{s^0}$ | $4{f^7}6{s^0}$ |
| Dy | +3,+4 | $4{f^10}6{s^2}$ | - | $4{f^9}6{s^0}$ | $4{f^8}6{s^0}$ |
| Ho | +3 | $4{f^11}6{s^2}$ | - | $4{f^10}6{s^0}$ | - |
| Er | +3 | $4{f^12}6{s^2}$ | - | $4{f^11}6{s^0}$ | - |
| Tm | +2,+3 | $4{f^13}6{s^2}$ | $4{f^13}6{s^0}$ | $4{f^12}6{s^0}$ | - |
| Yb | +2,+3 | $4{f^14}6{s^2}$ | $4{f^14}6{s^0}$ | $4{f^13}6{s^0}$ | - |
| Lu | +3 | $4{f^14}5{d^1}6{s^2}$ | - | $4{f^14}6{s^0}$ | - |
Table: Outer electronic configuration and oxidation states of lanthanum and lanthanides.
- Lanthanum show only $+3$ most stable oxidation state by losing two electrons from $6s$ and one from $5d$ orbital have the configuration of $Xe$.
- Gadolinium form only $+3$ most stable oxidation state ($G{d^{ + 3}} - [Xe]4{f^7}$) due to half filled stability of $'f'$ subshell.
- Lutetium also form only $+3$ oxidation state due to extra stability of completely filled $4f$ ($L{u^{ + 3}} - [Xe]4{f^{14}}$).
- Cerium $(Ce)$, Terbium $(Tb)$ attains $4{f^0}$ and $4{f^7}$ by losing four electrons form $C{e^{ + 4}}$ and $T{b^{ + 4}}$. having extra stability due to empty and half filled configuration.
- $E{u^{ + 2}}$ ($4{f^7}$) and $Yb$ ($4{f^14}$) are stable respectively due to extra stability of half filled and completely filled $4f$ subshells.
- Stability of $S{m^{ + 2}}$ and $T{m^{ + 2}}$ are explained on the basis of thermodynamic properties.
- The di-positive ions like $S{m^{ + 2}}$, $E{u^{ + 2}}$, $Y{b^{ + 2}}$ behaves as a reducing agent and ions like $C{e^{ + 4}}$ and $T{b^{ + 4}}$ acts as a good oxidizing agents.
- Most of the $+2$ and $+4$ ions of lanthanoids have not $4{f^0}$, $4{f^7}$ or $4{f14}$ electronic configuration e.g. $P{r^{ 4}}$($4{f^1}$), $N{a^{ + 2}}$($4{f^4}$), $S{m^{ + 2}}$($4{f^6}$), $D{y^{ + 4}}$($4{f^8}$).
