JEE Main Study Notes for d and f Block Elements

    Urvashi Singhal Urvashi Singhal
    Exams Prep Master

    Inorganic chemistry carries a bit low weightage as compared to organic and physical chemistry in JEE Mains question paper. But it is this section which is considered to be very easy, scoring and less time taking by the test takers. The biggest advantage of this section is that maximum number of times, it is directly from NCERT. Thus, all JEE Main test takers advise to consider NCERT as bible for inorganic chemistry. Read preparation tips for JEE Main Chemistry 

    • The chapter on d & f block elements carries a weightage of around 8.33% in JEE Main papers (the number of questions that have appeared in each year in JEE Main has been given below).
    • Questions are based on topics like Isomerism (Structural, Geometrical, Linkage, Optical Isomerism), Lanthanoid Contraction, Nomenclature and Crystal Field Theory.
    Periodic Table111
    Chemical Bonding42223
    d & f block212
    Qualitative Analysis1112
    Coordination Compound21211

    Read the article to find necessary preparation notes on d & f block elements that will help you build a strong base in this section.

    Must Read:

    What are d-block elements?

    The elements in which the last differentiating electron enters into the d-orbitals of the penultimate shell i.e. (n–1) d where n is the last shell are called d-block elements. A transition element may also be defined as the element which partially filled d-orbital in their ground state or most stable oxidation state.

    Cu (Z = 29) = 1s2 2s2 2p6 3s2 3p6 3d10 4s1

    Cu2+ = 1s2 2s2 2p2 3s2 3p6 3d9

    (Cupric ion)

    The properties of these elements are intermediate between the properties of s-block and p-block elements.

    These elements represent a change or transition in properties from more electropositive elements (s-block) to less electropositive elements (p-block). Therefore these elements are called transition elements.

    Position of d-block elements in periodic table

    Position in the periodic table

    The position of d-block element has been shown in periodic table as follows :

    Electronic Configuration

    Electronic Configuration

    (1) In d-block elements with increase in atomic number, the d- orbitals of penultimate shells i.e. (n-1) d are gradually filled by electrons. The general electronic configuration of d- block element is  (n-1)d1–10.ns0, 1, 2.

    (2) Depending upon the d-orbitals of which penultimate shell i.e. n = 4, 5, 6, 7 are filled, four rows (called series) os ten elements each obtained. They correspond to 3d, 4d, 5d and 6d subshells.

    (3) Energy of ‘(n–1)d’ subshell is slightly greater than ‘ns’ subshell, hence the orbital is filled first then (n – 1) d orbitals.

    (4) The general electronic configuration of d-block/d-series elements be shown as follows:

    First (3d) Transition Series (Sc–Zn)

    Second (4d) Transition Series (Y-Cd)

     Third (5d) Transition Series (La–Hg)

    Fourth (6d) Transition Series

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    Physical Properties of Transition Elements

    General Physical Properties of Transition Elements

    Atomic Radii

    1. The atomic radii of the transition metals lie in-between those of s- and p-block elements.
    2. Generally the atomic radii of d-block elements in a series decrease with increase in atomic number but the decrease in atomic size is small after midway.
    3. At the end of the period, there is a slight increase in the atomic radii.
    4. The atomic radii increase down the group. This means that the atomic radii of the second series are larger than those of the first transition series. But the atomic radii of the second and third transition series are almost the same.

    Ionic Radii

    1. The trend followed by the ionic radii is the same as that followed by atomic radii.
    2. Ionic radii of transition metals are different in different oxidation states.
    3. The ionic radii of the transition metals are smaller than those of the representative elements belonging to the same period.

    Metallic Character

    Except for mercury which is a liquid, all the transition elements have typical metallic structure. They exhibit all the characteristics of metals. ductile, have high melting and boiling points, high thermal and electrical conductivity and high tensile strength.

    Melting Point

    Transition metals have high melting points which is due to their strong metallic bond.

    Oxidation State

    1. With the exception of few elements, most of the d-block elements show more than one oxidation state i.e. they show variable oxidation states.
    2. All transition elements show variable oxidation state except the last element in each series.
    3. Minimum oxidation state = Total number of electrons in 4s lost. Maximum oxidation state = (Total number of electrons in 4s + number of unpaired electrons in 3d lost).
    4. The highest oxidation state is shown by Ruthenium (Ru) and Osmium (Os) i.e. +8.
    5. Across the period the oxidation state increases and it is maximum at the centre and then decreases even if the atomic number increases. The element which shows highest oxidation state occurs in the middle or near the middle of the series and then decreases.
    6. Transition metals also show zero oxidation states in metal carbonyl complex. (Nickel tetracarbonyl). Example : Ni in Ni (CO)4 has zero oxidation state.
    7. The bonding in the compounds of lower oxidation state (+2, +3) is mostly ionic and the bonding in the compounds of higher oxidation state is mostly covalent.

    What are f block elements?

    What are f block elements?

    f –block elements are also called inner transition elements. In these the last electron enters penultimate i.e. (n – 2)f f orbital. The differentiating electron in transition elements may enter either 4f or 5f orbitals based upon which they are differentiated into lanthanides and actinides.

    Lanthanides: In lanthanides the differentiating electron enters 4f orbital. These are cerium to lutetium. The name lanthanides is because they come immediately after lanthanum.

    Actinides: In actinides the differentiating electron enters 5f orbitals. These are thorium to lawrencium. These elements come immediately after actinium.

    Electronic configuration: General electronic configuration of f – block elements is (n–2)f1–14(n–1)d0–1ns2

    • Lanthanides: [Xe]4f1–145d0–16s2
    • Actinides: [Rn]5f1–146d0–17s2

    Solved Examples of d & f Block Elements

    Solved Examples of d & f Block Elements

    Ques. Which of the 3d series of the transition metals exhibits the largest number of oxidation states and why ?

    Ans. Manganese (Z = 25), as it atoms has the maximum number of unpaired electrons. 

    Ques. Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number ?

    Ans. In transition elements, there are greater horizontal similarities in the properties in contrast to the main group elements because of similar ns2 common configuration of the outermost shell.

    An examination of common oxidation states reveals that accepts scandium, the most common oxidation state of first row transition elements is +2 which arises from the loss of two 4s electrons. This means that after scandium, d-orbitals become more stable than the s-orbital.

    Further, +2 state becomes more and more stable in the first half of first row transition elements with increasing atomic number because 3d orbitals acquire only one electron in each of five 3d orbitals (i.e. remains half filled) and electronic repulsion is the least and nuclear charge increases. In the 2nd half of first row transition elements, electrons start pairing up in 3d orbitals. (Ti2+ to Mn2+ electronic configuration changes from 3d2 to 3d5 but in 2nd half i.e. Fe2– to Zn2+ it changes from d6 to d10)..

    Ques. What are the characteristics of the transition elements and why are they called transition elements ? Which of the d-block elements may not be regarded as the transition elements?

    Ans. The important characteristics of transition metals are:

    (i) All transition elements are metallic in nature, e.g., all are metals.

    (ii) These metals exhibit variable oxidation states.

    (iii) Transition metal atoms or ions generally form the complexes with neutral, negative and positive ligands.

    (iv) Compounds of transition metals are usually coloured.

    (v) The compounds of these metals are usually paramagnetic in nature.

    (vi) Transition metals and their compounds act as good catalysts, i.e., they show catalytic activities.

    (i) These metals form various alloys with other metals of the series.

    (ii) These metals form interstitial compounds with C, N, B and H.

    Ques. On what ground can you say that scandium (Z = 21) is a transition element but zinc (Z = 30) is not ?

    Ans. On the basis of incompletely filled 3d orbitals in case of scandium atom is its ground state (3d1), it is regarded as a transition element. On the other hand, zinc atom has completely filled d orbitals (3d10) in its ground state as well as in its oxidised state, hence it is not regarded as a transition element.

    Points to remember while studying chemistry

    • Chemistry is often considered as a scoring subject in JEE MAINS by most of the candidates. The difficulty curve of the questions remains mainly the same as they ask theoretical than calculative questions, making it the quickest subject to solve.
    • Planning is key while preparing to study chemistry for JEE, in fact the students need to be well versed with concepts such as formulas, named reactions, chemical equations, and periodic table trends and other topics that have more weightage.
    • Developing a clear understanding of the fundamental concepts is crucial in solving chemistry problems and scoring higher marks. Possessing a strong conceptual framework along with studying in a smart and strategic manner will benefit the students to the fullest.
    • For physical chemistry, first go through the concept and then understand the formulas. Resolve the question on each formula. Make a small notebook and make a list of all the chapter formulas wise in that notebook. There are chapters when you come to Inorganic Chemistry if you command on, then this portion of chemistry will be easier. One of the biggest tips for studying inorganic chemistry is to properly learn the periodic table. Then you will not be leaving even a single question unanswered from this portion in JEE. To easily learn the table use abbreviations or songs {Example- Oh (O-Oxygen) saan (S- Sulphur) se (Se- Selenium) te (Te- Tellurium)} to make learning more fun and interesting.



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