The D and F Block Elements - Notes, Topics, Formula, Books, FAQs
The D and F Block Elements - Notes, Topics, Formula, Books, FAQs
Edited By Team Careers360 | Updated on Dec 20, 2024 05:36 PM IST
The d- and f- block elements are the elements in which the electrons entered into the d-orbitals and f-orbitals respectively. These elements have the general electronic configuration as (n-1)d 1-10ns1-2 and (n-1)f1-14(n-1)d 1-2ns2. In this chapter, topics discussed includes various properties and general trends shown by d- and f- block elements 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.
The D and F Block Elements - Notes, Topics, Formula, Books, FAQs
Important Topics for d - and f - Block Elements
Transition Elements
Transition elements are located in groups 3 to 12 of the periodic table and are characterized by the presence of partially filled d-orbitals. These elements shows unique properties such as variable oxidation states, high melting and boiling points, and the formation of coloured compounds. Transition elements also serve as catalysts due to their ability to adopt multiple oxidation states.
Colour of Transition Elements
The colour of transition elements arises from the d-d electron transitions within the partially filled d-orbitals. When light interacts with these compounds, certain wavelengths are absorbed, and the complementary colours are reflected. This phenomenon is influenced by factors like oxidation state, ligand type, and geometry of the complex.
Properties of Interstitial Compounds
Interstitial compounds are formed when small atoms like hydrogen, carbon, or nitrogen occupy interstitial spaces within the metallic lattice of transition metals. Properties are Interstitial compounds are important to understand as these compounds exhibit high melting points, increased hardness, and chemical stability. Examples include titanium hydride and tungsten carbide, which are widely used in industrial applications.
Potassium permanganate is a strong oxidizing agent widely used in chemical reactions and water treatment. It acts as an oxidant in both acidic and alkaline conditions. The deep purple colour of KMnO4 solutions is due to the transition of electrons within the manganese ion's d-orbitals.
Potassium Dichromate (K2Cr2O7)
Potassium dichromate is another powerful oxidizing agent, often used in laboratory redox reactions and analytical chemistry. In acidic conditions, it converts to chromium(III) ions, producing a characteristic orange colour that transitions to green during reduction.
F-Block Elements
F-block elements are also known as lanthanides and actinides and are characterized by the filling of f-orbitals. Lanthanides are known for their magnetic, optical, and catalytic properties, while actinides are largely radioactive. These elements are widely used in industries, such as phosphors in LED lights and nuclear reactors for energy production.
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 1-10ns1-2. 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.
I Series of d-block elements
Atomic number
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
21
22
23
24
25
26
27
28
29
30
4s
2
2
2
1
2
2
2
2
1
2
3d
1
2
3
5
5
6
7
8
10
10
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:
Sc
Those
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
+3
+2
+2
+2
+2
+2
+2
+2
+1
+2
+3
+3
+3
+3
+3
+3
+3
+2
+4
+4
+4
+4
+4
+4
+4
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:
Ion
Configuration
Unpaired electron
Magnetic moment
Sc3+
3d0
0
0
Ti3+
3d1
1
1.73
Ti2+
3d2
2
2.84
V2+
3d3
3
3.87
Cr2+
3d4
4
4.90
Mn2+
3d5
5
5.92
Fe2+
3d6
4
4.90
Co2+
3d7
3
3.87
Ni2+
3d8
2
2.84
Cu2+
3d9
1
1.73
Zn2+
3d10
0
0
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.
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.
1.Why are transition elements called d-block elements?
Transition elements are called d-block elements because their last electron enters the d-subshell of the penultimate energy level. This characteristic is responsible for their unique properties like variable oxidation states and coloured compounds.
2.Why do transition elements form coloured compounds?
The colour of transition metal compounds arises due to d-d electronic transitions within partially filled d-orbitals. When light is absorbed, specific wavelengths are absorbed, and the complementary colour is observed.
3.What are interstitial compounds, and how are they formed?
Interstitial compounds are formed when small atoms like hydrogen, carbon, or nitrogen occupy the interstitial spaces in the metallic lattice of transition metals. These compounds exhibit enhanced hardness, high melting points, and resistance to corrosion.
4.How does KMnO4 act as an oxidizing agent?
KMnO4 acts as a strong oxidizing agent by undergoing reduction, where manganese changes its oxidation state from +7 to +2 (acidic medium) or +4 (neutral/alkaline medium). It oxidizes substances by accepting electrons.
5.Why are transition metals good catalysts?
Transition metals are good catalysts due to their ability to change oxidation states and provide a surface for reactants to adsorb and react. Their incomplete d-orbitals also facilitate the formation of intermediate complexes, accelerating reactions.
6.Why are transition elements called d-block elements?
Transition elements are called d-block elements because their last electron enters the d-subshell of the penultimate energy level. This characteristic is responsible for their unique properties like variable oxidation states and coloured compounds.
7.Why do transition elements form coloured compounds?
The colour of transition metal compounds arises due to d-d electronic transitions within partially filled d-orbitals. When light is absorbed, specific wavelengths are absorbed, and the complementary colour is observed.
8.What are interstitial compounds, and how are they formed?
Interstitial compounds are formed when small atoms like hydrogen, carbon, or nitrogen occupy the interstitial spaces in the metallic lattice of transition metals. These compounds exhibit enhanced hardness, high melting points, and resistance to corrosion.
9.How does KMnO4 act as an oxidizing agent?
KMnO4 acts as a strong oxidizing agent by undergoing reduction, where manganese changes its oxidation state from +7 to +2 (acidic medium) or +4 (neutral/alkaline medium). It oxidizes substances by accepting electrons.
10.Why are transition metals good catalysts?
Transition metals are good catalysts due to their ability to change oxidation states and provide a surface for reactants to adsorb and react. Their incomplete d-orbitals also facilitate the formation of intermediate complexes, accelerating reactions.
n is the number of electrons.