The d and f block Elements Formula

Location: These elements are positioned between s- and p-block elements in the periodic table, spanning periods 4 through 7 and groups 3 through 12. In these elements, the differentiating electron enters into d and f orbitals of outermost shell of an atom and hence are called d and f block elements

Characteristics of d-block Elements

The general electronic configuration of d-block elements is ns ^1-2 (n-1)d ^1-10

Where 'n' stands for the principal quantum number of the outermost shell.

3d series- Sc to Zn

4d series- Y to Cd

5d series-Hf to Hg

For example:

Chromium (Cr): [Ar] 4s ¹ 3d ⁵

Iron (Fe): [Ar] 4s ² 3d ⁶

Variable Oxidation States: Transition metals often exhibit multiple oxidation states.

Catalytic Properties: Many d-block elements and their compounds are known to act as catalysts in various chemical reactions.

Colored Compounds: Transition metal compounds often display vibrant colors due to d-d transitions.

High Melting and Boiling Points: This is due to the presence of unpaired electrons in the d orbitals, leading to stronger metallic bonding.

Magnetic Properties: Due to the presence of unpaired electrons, some transition metals exhibit paramagnetic behavior.

Examples: Iron (Fe), Copper (Cu), Silver (Ag), Gold (Au), and Zinc (Zn) are some examples of d-block elements.

Magnetic Moment (µ):

The magnetic moment of a compound containing unpaired electrons can be calculated using the formula:

√n(n + 2) ​ Bohr magnetons (B.M.)

Where:

n = total number of unpaired electrons in the ion or compound. For d-block elements, most often we consider only spin magnetism, ignoring the contribution from orbital magnetism, especially when the ligand field is strong. This is often termed the "spin-only" formula.

For example, Mn ²⁺ ion has 5 unpaired electrons.

Using the formula: √5(5 + 2) = √ 35 ≈ 5.92 B.M

Melting Points:

3d series: Increases from Sc to Cr and then gradually decreases to Zn. 4d & 5d series: Generally, the melting points decrease as you go from the 4d to 5d series.

Ionization Enthalpies: Increase across a period due to an increase in effective nuclear charge (from left to right).

Oxidation States:

3d series: Starts from +2(for Sc) and can go up to +7(for Mn). However, after Mn, the highest oxidation state decreases. Generally, the maximum oxidation state increases with a period and then decreases.

Standard Electrode Potentials: Varies irregularly across a transition series.

f-block Elements (Inner Transition Metals)

Location: These elements are typically placed at the bottom of the periodic table, separated into two series:

Also Check – Molecular Speed Formula

Lanthanides

These span from atomic number 57 (Lanthanum, La) to 71 (Lutetium, Lu).

The general electronic configuration is [Xe]6s ² 4f ^1-14

Melting Points: There isn't a clear trend. Some lanthanides, like Ce and Gd, have notably high melting points.

Ionization Enthalpies: Steadily increase with an increase in atomic number. Oxidation States: Predominantly +3 for most lanthanides. Some like Ce and Eu also exhibit +4 and +2 states, respectively.

Standard Electrode Potentials: The electrode potentials become less negative as we move from La to Lu.

High Magnetic Susceptibility: Particularly in the lanthanides due to unpaired 4f electrons.

Also Check – Mass Percent Formula

Actinides

These span from atomic number 89 (Actinium, Ac) to 103 (Lawrencium, Lr).

The general electronic configuration is [Rn]7s ² 5f ^1-14 6d ^0-1

Characteristics:

Rapid Filling of 4f and 5f Orbitals: The f-block elements involve the filling of the 4f and 5f orbitals.

Melting Points: Generally decrease as you move across the series. Thorium has one of the highest melting points.

Ionization Enthalpies: Similar to lanthanides, ionization enthalpies increase across the series.

Oxidation States: Varies widely, with +3 being common. However, elements like U, Np, and Pu can have oxidation states ranging from +3 to +6.

Standard Electrode Potentials: Actinides have a wide range of E₀ values due to their varied oxidation states. Generally, they become less negative as you progress down the actinide series.

Similar Properties: Elements within the lanthanide and actinide series have very similar properties, making their separation and distinction challenging. Radioactivity: Many of the actinides are radioactive.

Also Check – Ionization Energy Formula

Actinide Series Radioactive Decay

Uranium and Thorium undergo a series of radioactive decay processes before becoming stable lead isotopes.

For example:

Uranium-238 decays to Thorium-234 through alpha decay

92238U → 90234Th + 24He