d and f-Block Elements Quiz
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Questions and Answers

Which characteristic of transition elements contributes to their strong metallic bonding?

  • The presence of one or two labile $ns^1$ or $ns^2$ electrons. (correct)
  • Their oxidation states.
  • The absence of unpaired electrons.
  • The presence of paired $d$ electrons.

    • Why do Cr, Mo, and W exhibit high hardness among transition metals?

  • Due to their low enthalpy of atomization.
  • Due to the large number of unpaired electrons that strengthens bonding. (correct)
  • Due to their smaller atomic radii.
  • Due to the absence of $d$ electrons.

    • What factor contributes to the relatively lower hardness of Zn, Cd, and Hg compared to other transition metals?

  • The presence of unpaired electrons, leading to strong overlap.
  • They have very high enthalpy of atomization.
  • The absence of unpaired electrons, resulting in weaker metallic bonding. (correct)
  • The presence of $f$ electrons.

    • How do the ionization energies of transition elements compare to those of s-block and p-block elements?

    <p>Higher than s-block elements but lower than p-block elements. (A)</p> Signup and view all the answers

    What is the primary reason for the gradual increase in ionization energy across a transition series?

    <p>Increase in nuclear charge. (C)</p> Signup and view all the answers

    Why is the increase in ionization energy not very significant across the period of d-block elements?

    <p>Due to the screening effect of the gradually filling $(n-1) d$-orbitals. (B)</p> Signup and view all the answers

    What accounts for the higher ionization energies of 5d-transition elements compared to 3d- and 4d-transition elements?

    <p>Ineffective shielding of the nucleus by 4f-electrons. (C)</p> Signup and view all the answers

    What information can be estimated from the magnitude of ionization energy values of transition elements?

    <p>The relative stabilities of various oxidation states of metals. (D)</p> Signup and view all the answers

    What causes the color in transition metal complexes?

    <p>Absorption of specific wavelengths of visible light for d-d electronic transitions. (C)</p> Signup and view all the answers

    Why do d-orbitals split into different energy levels in transition metal complexes?

    <p>Under the influence of the ligands attached to the metal ion. (C)</p> Signup and view all the answers

    Which electronic configuration would typically result in a colorless complex?

    <p>d¹⁰ (B)</p> Signup and view all the answers

    What is the relationship between absorbed and transmitted light in colored complexes?

    <p>Absorbed and transmitted light together constitute white light. (B)</p> Signup and view all the answers

    In the complex ion $[Ti(H₂O)₆]^{3+}$, why does it appear violet?

    <p>It absorbs yellow light and transmits violet light. (D)</p> Signup and view all the answers

    What determines whether a transition metal complex will exhibit color?

    <p>The ability of electrons to undergo d-d transitions. (B)</p> Signup and view all the answers

    What is the relative energy of $e_g$ orbitals compared to $t_{2g}$ orbitals in an octahedral complex?

    <p>$e_g$ orbitals have higher energy than $t_{2g}$ orbitals. (A)</p> Signup and view all the answers

    Why are $Zn^{2+}$ salts white?

    <p>They have filled d-orbitals which prevent d-d transitions. (B)</p> Signup and view all the answers

    What occurs after the d⁵ configuration in d-orbitals?

    <p>Paired electrons in d-orbitals begin to experience repulsive interactions. (C)</p> Signup and view all the answers

    What causes the elements of the second and third transition series to have similar atomic radii?

    <p>The effects of lanthanide contraction. (C)</p> Signup and view all the answers

    How are the variable oxidation states of transition metals primarily determined?

    <p>From the participation of ns and (n-1)d electrons in bonding. (D)</p> Signup and view all the answers

    What is a characteristic feature of complex compounds formed by transition elements?

    <p>They link metal ions with molecules/ions through co-ordinate bonds. (D)</p> Signup and view all the answers

    What contributes to the tendency of transition metals to form complexes?

    <p>A high charge density and small size of their ions. (D)</p> Signup and view all the answers

    What is one reason that transition metal compounds are usually colored?

    <p>They have partially filled d-orbitals that allow for electron transitions. (B)</p> Signup and view all the answers

    In which type of bonding do ligands participate when forming complex compounds with transition metals?

    <p>Co-ordinate bonding (B)</p> Signup and view all the answers

    Why do transition metal ions have large effective nuclear charges?

    <p>Because of their higher atomic numbers and resulting electrostatic forces. (C)</p> Signup and view all the answers

    Why are Ni(II) compounds thermodynamically more stable than Pt(II) compounds?

    <p>The sum of the first two ionization energies is lower for nickel. (A)</p> Signup and view all the answers

    What does a smaller value of total enthalpy change, ∆HT, indicate about a metal's oxidation state in solution?

    <p>Greater stability of the oxidation state. (B)</p> Signup and view all the answers

    What factor influences the stability of a metal's oxidation state in aqueous solution alongside ionization energy?

    <p>Enthalpy of sublimation. (A)</p> Signup and view all the answers

    As the atomic number increases in the first transition series, what trend is observed in atomic radii?

    <p>Atomic radii decrease, remain constant, then increase. (A)</p> Signup and view all the answers

    What primarily causes the decrease in atomic radii at the beginning of the transition series?

    <p>Screening effect of d-orbital electrons. (D)</p> Signup and view all the answers

    In the context of transition metals, how do standard electrode potentials affect oxidation state stability?

    <p>Smaller standard electrode potentials indicate greater stability. (D)</p> Signup and view all the answers

    Which of the following factors does NOT influence the total enthalpy change, ∆HT?

    <p>State of oxidation of the metal. (B)</p> Signup and view all the answers

    Which compound is known to exist for platinum in the +4 oxidation state?

    <p>K₂PtCl₆ (C)</p> Signup and view all the answers

    Why is Cu2+ more stable than Cu+ in an aqueous solution?

    <p>Cu2+ has a higher hydration energy due to its small size and greater charge (D)</p> Signup and view all the answers

    What causes CuI2 to be highly unstable?

    <p>Cu2+ oxidizes iodide ion (I-) to I2 (C)</p> Signup and view all the answers

    What is the primary cause of the lanthanide contraction?

    <p>Ineffective shielding of f-orbital (B)</p> Signup and view all the answers

    What is the result of the lanthanide contraction on the basic character of hydroxides?

    <p>Decrease in basic character (C)</p> Signup and view all the answers

    Which ion has the highest stability in aqueous solution among Mn3+, Cr3+, and Ti3+?

    <p>Cr3+ due to its half-filled t2g3 orbital (D)</p> Signup and view all the answers

    Why is platinum(IV) more stable than nickel(IV)?

    <p>The sum of the first four ionisation energies for nickel is higher than for platinum (A)</p> Signup and view all the answers

    Which of the following statements accurately describes the ions of actinoids?

    <p>They are radioactive (D)</p> Signup and view all the answers

    Which transition metal exhibits the largest number of oxidation states?

    <p>Manganese since it has seven electrons available for bonding (B)</p> Signup and view all the answers

    What distinguishes silver as a transition element despite its filled d-orbitals?

    <p>It has an incomplete d-orbital in a higher oxidation state (A)</p> Signup and view all the answers

    Which ion is a stronger reducing agent: Cr2+ or Fe2+?

    <p>Cr2+ due to its oxidation to a more stable Cr3+ (C)</p> Signup and view all the answers

    Why do lanthanides show similar properties among themselves across periods?

    <p>Due to the lanthanide contraction (A)</p> Signup and view all the answers

    Which of the following elements is a notable exception to non-radioactivity in lanthanides?

    <p>Promethium (A)</p> Signup and view all the answers

    Why are transition metal oxides basic in their lowest oxidation state and acidic in their highest oxidation state?

    <p>Low oxidation states form ions while high states form covalent bonds (D)</p> Signup and view all the answers

    Why do transition elements commonly form colored compounds?

    <p>They have unpaired electrons that allow for color absorption (B)</p> Signup and view all the answers

    How does the metallic radius change across the transition elements from Sc to Cu?

    <p>It shows a small and irregular decrease (A)</p> Signup and view all the answers

    What property distinguishes transition elements from zinc, cadmium, and mercury?

    <p>They have incomplete d-orbitals (A)</p> Signup and view all the answers

    Flashcards

    Transition elements

    Metals with partially filled d-orbitals allowing metallic bonding.

    Metallic bonding

    Bonding due to overlapping of unpaired electrons in metals.

    Enthalpy of atomization

    Energy required to break the attractions between atoms in a substance.

    Soft metals

    Metals like Zn, Cd, and Hg with weaker metallic bonding due to fewer unpaired electrons.

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    Ionization energy

    Energy required to remove an electron from an atom.

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    Nuclear charge

    The total charge of the nucleus affecting electron shielding and ionization energy.

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    Effective nuclear charge

    Actual charge felt by an electron after accounting for screening by other electrons.

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    Oxidation state stability

    Indication of how stable a particular oxidation state of a metal is based on ionization energy.

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    Ionization Energy of Nickel vs. Platinum

    Nickel (Ni) has a lower sum of first two ionization energies than platinum (Pt), making Ni(II) more stable than Pt(II).

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    Stability of Pt(IV) vs. Ni(IV)

    Platinum (Pt) has a lower sum of first four ionization energies than nickel (Ni), making Pt(IV) more stable than Ni(IV).

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    K₂PtCl₆

    A well-known compound of platinum in the +4 oxidation state, while the corresponding nickel compound is not known.

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    Factors Determining Stability in Solutions

    The stability of a metal state in solutions is determined by ionization energy, enthalpy of sublimation, and lattice/solvation energies.

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    Total Enthalpy Change Equation (∆HT)

    The total enthalpy change (∆HT) is the sum of sublimation enthalpy, ionization energy, and hydration enthalpy: ∆HT = ∆HS + I.E. + ∆Hhyd.

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    Stability and Total Enthalpy Change

    A smaller value of total enthalpy change (∆HT) indicates greater stability of a metal's oxidation state in solution.

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    Electrode Potential (E°red) Relation

    A smaller standard electrode potential (E°red) corresponds to a more stable oxidation state of a metal in aqueous solution.

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    Atomic and Ionic Radii Trends

    In transition elements, atomic radii decrease, then stay constant, and finally increase across a period due to nuclear charge and electron effects.

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    d-orbital pairing

    Pairing of electrons in d-orbitals after d⁵ configuration, affected by electron repulsion.

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    Ionic radii trends

    Ionic radii of transition metals generally increase towards the end of periods due to repulsion and lanthanide contraction.

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    Lanthanide contraction

    Effect causing the atomic radii of second and third transition series to be nearly equal due to poor shielding of f-electrons.

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    Variable oxidation states

    Transition metals exhibit multiple oxidation states due to involvement of ns and (n-1)d electrons in bonding.

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    Lower oxidation state

    Generally shown when only ns-electrons participate in bonding, less energy needed.

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    Complex compounds

    Compounds containing a metal ion bonded to surrounding anions or neutral molecules via coordinate bonds.

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    Ligands

    Ions or molecules that donate electron pairs to form coordinate bonds with a central metal atom.

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    Color of transition-metal compounds

    Transition metal compounds are typically colored due to electronic transitions within d-orbitals.

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    Colour of Transition Compounds

    The colour is due to absorption of visible light for electron promotion.

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    d-Orbital Splitting

    d-orbitals split into two sets (eg and t2g) under ligand influence.

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    Electron Transition

    Electrons move from lower to higher d-orbitals within the same subshell.

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    Visible Light Absorption

    Energy needed for electron transition is in the visible light region.

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    Complimentary Color

    The emitted colour of a complex is the complementary color of the absorbed light.

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    Example: Titanium Salts

    Titanium salts are purple due to d¹ electron absorbing yellow light.

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    Zn²⁺ and Ti⁴⁺ Salts

    They are white because they do not absorb visible light; full or vacant d-orbitals.

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    Unpaired Electrons

    Presence of unpaired electrons in partially filled d-orbitals allows d-d transitions.

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    Effect on reducing agents

    Lanthanide contraction decreases the tendency of elements to act as reducing agents due to increased bond strength.

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    Basic character of hydroxides

    Lanthanide contraction leads to decreased basicity of hydroxides as size decreases and bond strength increases.

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    Color of ions

    Lanthanides form mostly colorless ions while actinides form colored ions.

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    Complex formation

    Actinides can easily form complexes while lanthanides do not.

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    Radioactivity

    Most actinides are radioactive, while lanthanides (except promethium) are not.

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    d and f block electronic configuration

    Transition elements have partially filled d-orbitals; f-block elements have f-orbitals filling sequentially.

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    Transition element definition

    Silver is a transition element despite filled d-orbitals due to its incomplete d-orbital in higher oxidation state.

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    Stability of Cu2+

    Cu2+ is more stable than Cu+ due to high hydration energy from its small size and higher charge.

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    Instability of CuI2

    CuI2 is unstable because Cu2+ oxidizes iodide ions (I-) to I2.

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    Unpaired Electrons in Ions

    Mn3+, Cr3+, and Ti3+ have unpaired electrons; Cr3+ is most stable due to half-filled t2g3 orbital.

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    Scandium Oxidation States

    Scandium does not show variable oxidation states as it achieves a stable inert gas configuration by losing three electrons.

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    Oxidation States of Manganese

    Manganese exhibits the largest number of oxidation states due to having seven valence electrons in its d and s orbitals.

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    Reducing Agents: Cr2+ vs Fe2+

    Cr2+ is a stronger reducing agent than Fe2+ because it oxidizes to a stable Cr3+ state with half-filled orbitals.

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    Acidity of Metal Oxides

    Lowest oxidation states of transition metals are basic while highest states are acidic due to bond types formed.

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    Study Notes

    d and f-Block Elements

    • The periodic table is divided into four blocks (s, p, d, and f) based on the orbital where the last electron enters.
    • Transition elements (d-block) are found in periods 4 and onwards and are elements with a partially filled d-orbital
    • The d-block elements exhibit a transition between the s- and p-block elements.
    • The d-block elements generally contain partially filled orbitals (except Zn, Cd, and Hg)
    • The f-block consists of the lanthanides and actinides
    • Lanthanides (4f-series) and Actinides (5f-series) show similar properties due to lanthanide contraction
    • Transition elements are hard, lustrous, malleable, ductile, and have high melting and boiling points; and are good conductors of heat and electricity
    • Transition elements have variable oxidation states.
    • Transition metals form many coloured compounds.
    • Transition elements have high enthalpy of atomization
    • Transition elements (especially those with unpaired electrons) form interstitial compounds
    • Transition elements act as good catalysts.

    Electronic Configuration of d-block elements

    • Electronic configuration of d block elements: (n-1)d1-10ns1-2
    • Electronic configuration of f block elements: (n-2)f1-14(n-1)d0-1ns0-2

    Exceptional Configurations of Cr and Cu

    • Chromium (Cr) and Copper (Cu) have anomalous electronic configurations to achieve greater stability by half-filled or fully-filled d-orbitals.
    • The greater stability of half-filled and fully filled d-orbitals is due to high exchange energy.

    Metallic Character

    • The metallic character of transition elements generally decreases across a series
    • Ionization energy increases gradually across a period. The relative difference in ionization energy between consecutive d-block elements is much smaller compared to s and p block elements.
    • The energy required to increase the oxidation state of the transition elements increases gradually.
    • Transition elements exhibit variable oxidation states due to the participation of ns and (n-1)d electrons in bonding.
    • The variable oxidation states of transition elements is due to the participation of ns and (n-1)d electrons in bonding.
    • The lower oxidation state is generally exhibited when ns electrons participate in bonding and higher oxidation states are shown when both ns and (n-1)d electrons participate in bonding together.
    • Transition metal ions generally form coloured compounds in solution.

    Complex Formation

    • Complex compounds are compounds where a metal ion is linked to a number of anions or neutral molecules called ligands through coordinate bonds.
    • The tendency to form complexes is greater in transition metals due to their small size and high charge density, vacant orbitals and large effective nuclear charge.

    Atomic and Ionic Radii

    • Atomic radii of transition elements lie between those of s and p block elements and first decrease, then remain almost constant, and then increase across the period
    • This pattern is due to the increasing nuclear charge and the effect of the screening of d electrons. In the case of the lanthanides (4f electron filling) the atomic radii continuously decrease which is known as Lanthanide Contraction.

    Oxidation States

    • Transition metals exhibit a wide variety of oxidation states.
    • The variable oxidation states are due to the participation of ns and (n-1)d electrons in bonding.

    Other Properties

    • Alloy formation: The similar atomic sizes of transition elements allow one element to take positions in another's crystal lattice
    • Catalytic properties: Transition metals act as catalysts due to their ability to form unstable intermediate complex with reactants and the availability of empty d-orbitals
    • Interstitial compounds: Atoms of hydrogen, carbon, and nitrogen fill the spaces within the lattice of transition metals.
    • Magnetic properties: Transition metals are often paramagnetic due to unpaired electrons.

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    D and F Block Elements Notes 2024-25 PDF

    Description

    Test your knowledge on d and f-block elements from the periodic table. This quiz covers key properties, characteristics, and trends of transition metals and lanthanides/actinides. Explore how these elements interact and their significance in chemistry.

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