The D and F Block Elements - Notes, Topics, Formula, Books, FAQs

The d- and f- block elements are the elements whom the electrons entered into the d-orbitals and f-orbitals respectively. These elements have the general electronic configuration as (n-1)d ^1-10ns^{1-2 and} (n-1)f^1-14(n-1)d ^1-2ns². In this chapter, you will learn about the various properties and general trends which are shown by these elements. Many of the important elements that we come across in our daily life are the members of this family like iron, zinc, copper, gold, etc. These elements are known as transition elements because their properties are in between the s-block elements and the p-block elements. But there are some elements like zinc, cadmium, and mercury which have always completely filled d orbitals, thus these elements are not considered as transition elements.

There are various real-life applications related to d- and f-block elements that we come across in our life. Some of them are mentioned below.

• Many of the d-bock elements form the complex compounds that we use in our daily life such as ruby, sapphire, etc.
  
• In the actinoids series, there are various elements that are radioactive like uranium. This uranium undergoes nuclear fission reaction.
  

• In black and white photographs, the film is washed to dissolve silver bromide and form a silver complex.
  
  

Notes for d- and f-block Elements

In this section, you will study about the important topics of the chapter, overview, formulae and some important tips and guidelines for the preparation of the chapter at the best.

Important Topics - d - and f - Block Elements

• Position in the Periodic Table

• General properties of the d-block elements

• Some important compounds of d-block elements

• The Lanthanoids

• The Actinoids

• Some applications of d- and f-block elements

Overview of the chapter

Position of d-block elements in the periodic table

In the modern form of the periodic table, d-block elements lie between group 3 to group 12. The general electronic configuration of these elements is (n-1)d ^1-10ns^1-2. This d orbital always fill after the s orbital but in some exceptional cases like Cr and Cu with electronic configurations are 3d⁵ 4s¹ and 3d¹⁰ 4s¹ respectively, this is because half-filled orbitals are more stable than other cases and the energy difference between the 4s and 3d orbitals is not significant thus it becomes easier for electron to go to 3d orbital instead of 4s.

General properties of the d-block Elements

• Physical properties: All the metals of d-block elements have almost the same physical properties. They all have high tensile strength, ductility, metallic luster and high thermal and electrical conductivity.

• Atom and Ion Size: The atomic and ionic sizes of these elements follow the same order as we have discussed in our previous chapter - ‘Atomic structure’. As expected, the atomic sizes decrease as we move from left to right in a period and it increases as we move from I(3d) series to II(4d) series. But as we move from II(4d) to III(5d) series, there is no significant increase in the atomic size. This is because, in 5d series, the filling of the f-orbitals occurs before the d-orbitals. Since the electron in f­-orbitals has very poor shielding to other electrons, thus due to increase in nuclear charge the atomic size decreases, this is also known as Lanthanoid contraction and thus, unexpectedly, 4d elements and 5d elements have an almost similar size.

• Ionization Enthalpies: The ionization enthalpies of d-block elements increases in a period. The first three ionization enthalpies of first row elements of d-block elements are given in the table below.

  Sc	Ti	V	Cr	Mn	Fe	Co	Ni	Cu	Zn
  631	656	650	653	717	762	758	736	745	906
  1235	1309	1414	1592	1509	1561	1644	1752	1958	1734
  2393	2657	2833	2990	3260	2962	3243	3402	3556	3829

• Oxidation States: The d-block elements show variable oxidation states. Usually, the element in the period has the maximum number of oxidation states than any other elements in the period and the minimum number of oxidation states are shown by elements at the extreme. The cause of the variable oxidation states of these elements is their incompletely filled d-orbital due to which electrons get easily shift to the d-orbital and thus they show variable oxidation states.
  Oxidation states of first row of transition elements:

• Magnetic Properties:
  For any kind of physical matter, on the application of the magnetic field, only two kinds of magnetic behavior are observed i.e paramagnetism and diamagnetism. Paramagnetic substances are those which are attracted by the magnet and diamagnetic substances are those which are repelled by the magnet. The magnetic behavior of the substances is determined by the presence of unpaired electron. If the substance has no unpaired electron, then it is diamagnetic otherwise it is paramagnetic.

The magnetic moment of any substance is given by the following formula:
n is the number of electrons.Magnetic moments of some ions:

• Formation of Complex Compounds and their colour: The d-block elements form a large number of complex compounds. Complex compounds are those in which the central metal atom is bind by ions or neutral molecules and form a complex entity. Some common examples are [Fe(CN)₆]^3- and [PtCl₄]^2-.

These complex compounds absorb some wavelength of light as it passes through these compounds. Thus the colour observed from these compounds is complementary to the wavelength of the absorbed light.

• Alloy Formation: An alloy is a substance that is formed by mixing of two or more metals together. These alloys are better in their properties than their parent metals. They are hard and have high melting points. Some of the common examples of alloys are stainless steel, brass, bronze, etc.

Some important compounds of d-block elements

Most of the transition elements form their various oxides. These oxides differ in the oxidation number of elements. Some of the important compounds of transition elements include potassium dichromate(K₂Cr₂O₇), potassium permanganate(KMnO₄).

The Lanthanoids
As mentioned earlier, lanthanoids are those elements that start with lanthanum with atomic number 57 till lutetium with atomic number 71. These elements have their outermost electrons in the f-orbitals.

Atomic Radius
In lanthanoids, the atomic radius decreases from left to right. Basically, in lanthanoids, the electrons are in the f-orbitals. These f-orbitals have poor shielding effect. Now as the atomic increases and shielding effect is poor, thus the atomic radius decreases from left to right. This decrease of atomic size due to poor shielding effect is known as lanthanoid contraction.

Oxidation States
Like the d-block elements, these elements also show variable oxidation states. This variability of oxidation states is because of the availability of f-orbital electrons. Due to the half-filled and fully-filled f-orbitals, these elements show variable oxidation states.

Physical Properties: There are some of the important physical properties of lanthanoids as mentioned below:

• Lanthanoids are silvery-white soft metals.

• Their hardness increases with increasing atomic number.

• Their melting points usually high ranging between 1000 to 1200 K.

• They are good conductors of heat and electricity.

• Lanthanoids are used for the production of alloy steels.

The Actinoids

The Actinoids are the group of elements that have outermost electrons in the 5f orbital. These elements are 14 in total from Thorium to Lawrencium. The actinoids are radioactive elements and their initial members have little long half-life but the latter members have very short half-lives.

Some applications of d- and f-block Elements

There are various important compounds of d- and f-block elements and their uses as mentioned below:

• Iron and steel are the most important elements of this group. They are used for various purposes such as in building homes, pillars, shaving blade, etc.

• Gold is also an important element of this group. It is used in making jewelry and other kinds of ornaments.

• Copper and silver are used for making coins.

• Many of the d-block elements and their compounds are important catalysts in various chemical reactions, such as V₂O₅ acts as catalysts in the oxidation of sulphur dioxide in the making of sulphuric acid.

• Complex compounds of nickel are used in the polymerization of alkynes.

• The light-sensitive properties of AgBr play an important role in the photographic industry.

How to prepare for d- and f-block Elements?

• This chapter is a part of inorganic chemistry. It is completely theory-based and very easy to learn, no need to memorize any formula.

• Before reading this chapter, first, you must have the basic knowledge of chapter - periodic classification of elements.

• You should understand clearly the trends in the various properties of the elements like atomic size, ionization enthalpy, oxidation states, etc.

• Rest this complete chapter is very simple, just be regular and be consistent in your practice.

Prescribed Books

First, you must finish the class XI and XII NCERT textbook and solve each and every example and unsolved question given in it. Then for advanced level preparation like JEE and NEET, you must follow O.P. Tandon. You must definitely solve the previous year papers. Meanwhile, in the preparation, you must continuously give the mock tests for the depth of knowledge. Our platform will help you to provide with the variety of questions for deeper knowledge with the help of videos, articles and mock tests.