Notes on chemistry of d block elements

The f-block elements, also known as inner transition elements, are those elements in which the last electron that enters the f-orbital is known. Members of group 3 are commonly considered inner transition elements, but the f-block elements can be considered independent from group 3. This group of atoms has electrons in the f orbital (1-14), in the d orbital of the penultimate energy level (0-1), and the outermost’s orbital (outermost s orbital). The f block contains two series corresponding to the 4f and 5f orbitals’ filling up, respectively. 

f-block elements

The f-block elements are classified into two series: 

• Lanthanide: The lanthanide series includes elements with atomic numbers ranging from 57 to 71. These substances don’t emit any radiation (except for promethium). The 4f orbital is occupied by the last electron in the lanthanide family.
• Actinoids: The actinide series includes elements with atomic numbers ranging from 89 to 103, which is the second set of elements. In nature, most of these elements are radioactive. The last electron in the actinide series enters the orbital 5f.

These elements are classified as either lanthanide or actinides based on whether their last electron enters the 4f or 5f orbitals. This group of elements is referred to as the inner transition metals. They provide a transition between the s block and the d block elements in the 6th and 7th rows of the periodic table, located between the s block and the d block elements NCERT. We can also avail chemistry of d block elements by studying them.

What are Lanthanides?

A total of fourteen chemical elements, ranging from cerium to lutetium, are contained inside the 4f block, each with an atomic number ranging between 58 and 71. Because they exist after Lanthanum, these f-block chemical elements are called Lanthanum or rare-earth elements. In addition, the element lanthanum is classified as part of the lanthanide series because the Chemical and physical properties of fifteen elements ranging from 57La to 71Lu are strikingly similar.

Electronic Configuration of Lanthanide

 4f1-145p65d0-16s2 {from cerium(Z=53) to Lutetium(Z=71)}

Properties of Lanthanides:

• Metallic lanthanides have a silvery-white appearance and are soft metals.
• When exposed to air, their colour fades, and their brilliance diminishes.
• Temperatures ranging from 1000 K to 1200K are typical for these materials (Except Samarium, 1623K).
• Lanthanides excellent conductors of both heat and electricity and are widely used in electronic devices.
• There is a decrease in the atomic and ionic radii from lanthanum to lutetium. Lanthanide contraction refers to this process.

What are Actinides?

Five of the chemical elements in the 5f block, which range from thorium to lawrencium and have atomic numbers ranging from 90 to 103, are found in this block. Because they exist after actinium, these f-block elements are called actinides. Moreover, actinium is grouped with the actinide series because the physical and chemical properties of the fifteen elements in the actinide series (89Ac to 103Lw) are highly similar.

Electronic Configuration of Actinide

5f1-146s26p66d0-17s2{from thorium (Z = 90) to lawrencium (Z = 103)}

Properties of Actinide:

• In appearance, the Actinide elements have a silvery appearance to them.
• There is a radioactive element in this group of elements.
• Although highly reactive, some metals exhibit increased reactivity when finely split.
• From Actinium to Lawrencium, there is a drop in the atomic and ionic radii. The actinoid contraction is the term used to describe this process.
• A +3 oxidation state is typically observed in them. On the other hand, it is well-known that elements belonging to the first half of the series often exhibit more significant oxidation states.

Characteristics of f-block elements

The f-block elements are divided into two parts that are lanthanoids and actinoids.

• Lanthanides, for example, are chemical elements belonging to the f-block that behave as active metals when exposed to light. As a result, these elements have redox reaction potentials comparable to those of alkaline earth metals.
•  In chemical interactions with acids, all f-block elements are potent reducing agents, and the release of hydrogen ions is responsible for this. Thus, they collect hydrogen ions from solutions with low pH scales and create interstitial hydrides due to this interaction.
• The two series of f-block elements share many similarities, but they also have significant variances, including highly ineffectual ones. 

Electronic Configuration of f-block elements

It has been determined that the overall electronic configuration of f-block elements (lanthanum and actinium series) is (n – 2)f1-14(n – 1)d0-1ns2. Examples of electronic configurations of 4f-block elements are promethium (atomic number 61), which has the valence shell electronic configuration of 4f5 5d0 6s2, and thallium (atomic number 61).

What are the general properties of f-block elements?

• They have a wide range of oxidation states.
• They tend to form complicated chemicals.
• The inner transition elements’ third final shell is filled with electrons.
• These elements create colourful icons.
• Actinide series elements are radioactive.
• The inner transition elements display variable valencies.
• Beyond atomic number 92, elements are both synthetic and radioactive.

Similarities between Lanthanides and Actinides

Difference between Lanthanides and Actinides

Summary

The f-orbital is filled in the f-block elements. Inner-transition elements are a term used to describe these two sets. Elements’ characteristics are relatively similar within each series. Actinides are usually radioactive. The number of commercial applications for lanthanides is increasing at an alarming rate. 

Conclusion

The f block elements are those in which the differentiating electron enters the (n-2)f orbitals, the first of the two orbitals. Because of their position and features, they are also referred to as inner transition elements. They are classified as belonging to the third group of the periodic table. A total of two series of f block elements are available: the 4f series (lanthanoid) and the 5f series (actinoid).