Periodic Table: d-Block and f-Block Elements
43 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which of the following are typical metallic properties of transition elements?

  • Non-metallic lustre
  • Low thermal conductivity
  • High tensile strength (correct)
  • Low boiling points

    • Transition metals Zn, Cd, Hg, and Mn have typical metallic structures at normal temperatures.

    True

    What lattice structure is typically displayed by transition metal Fe?

    bcc

    Transition metals (except Zn, Cd, and Hg) are known for their high ______ and low volatility.

    <p>hardness</p> Signup and view all the answers

    Match the following transition elements with their respective lattice structures:

    <p>Titanium (Ti) = hcp Manganese (Mn) = hcp Iron (Fe) = bcc Nickel (Ni) = ccp</p> Signup and view all the answers

    What are the positions of the d– and f-block elements in the periodic table?

    <p>The d-block elements are in the middle section of the periodic table, flanked between s and p blocks. The f-block elements are placed separately at the bottom of the periodic table.</p> Signup and view all the answers

    What is the general trend in the electronic configurations of outer orbitals of d-block elements?

    <p>The general trend is (n-1)d ns, except for some exceptions such as Pd which has a configuration of 4d10 5s0.</p> Signup and view all the answers

    Why is Zinc not considered a transition element?

    <p>Zinc is not considered a transition element because it has fully filled d orbitals (3d10) in both its ground state and common oxidation states.</p> Signup and view all the answers

    How are the d-block elements influenced by their surroundings?

    <p>The d orbitals of d-block elements protrude more than other orbitals, making them more influenced by their surroundings and affecting nearby atoms or molecules.</p> Signup and view all the answers

    Why are transition elements different from non-transition elements?

    <p>Incompletely filled d or f orbitals</p> Signup and view all the answers

    Why is scandium(II) virtually unknown early in the series?

    <p>Too few electrons to lose or share</p> Signup and view all the answers

    Which transition element exhibits all the oxidation states from +2 to +7?

    <p>Manganese</p> Signup and view all the answers

    Copper liberates hydrogen gas from all types of acids.

    <p>False</p> Signup and view all the answers

    Name a transition element which does not exhibit variable oxidation states: ________

    <p>Scandium</p> Signup and view all the answers

    Why is the E value for copper positive?

    <p>Consider its high ∆aH and low ∆hydH</p> Signup and view all the answers

    Why do transition elements exhibit higher enthalpies of atomisation?

    <p>Due to the large number of unpaired electrons in their atoms, transition elements have stronger interatomic interactions and hence stronger bonding between atoms, resulting in higher enthalpies of atomisation.</p> Signup and view all the answers

    Why is the enthalpy of atomisation of zinc the lowest in the series Sc (Z = 21) to Zn (Z = 30)?

    <p>The enthalpy of atomisation of zinc is the lowest due to its value of 126 kJ mol^-1, which is lower compared to the enthalpies of atomisation of other elements in the series.</p> Signup and view all the answers

    Explain the trend in ionisation enthalpy along a series of transition elements.

    <p>Ionisation enthalpy increases along a series of transition elements from left to right due to an increase in nuclear charge as the inner d orbitals are being filled.</p> Signup and view all the answers

    Why are the ionisation enthalpies of transition elements less steeply increasing than non-transition elements?

    <p>The ionisation enthalpies of transition elements show less steep increase because the variation in nuclear charge experienced by the electrons is shielded to some extent by the 3d electrons, which effectively shield the 4s electrons.</p> Signup and view all the answers

    Why is Cu (aq) more stable than Cu (aq)?

    <p>due to the much more negative ∆hydH of Cu (aq) than Cu , which more than compensates for the second ionisation enthalpy of Cu</p> Signup and view all the answers

    What demonstrates the ability of oxygen to stabilize the highest oxidation state?

    <p>The oxides</p> Signup and view all the answers

    How would you account for the increasing oxidizing power in the series VO2 < Cr2O7 < MnO4?

    <p>Increasing stability of the lower species</p> Signup and view all the answers

    Transition metals are largely unaffected by mineral acids.

    <p>False</p> Signup and view all the answers

    Calculate the 'spin only' magnetic moment of Mn2+ ion (Z = 25).

    <p>5.92 BM</p> Signup and view all the answers

    What determines the frequency of light absorbed in the excitation of an electron from a lower energy d orbital to a higher energy d orbital?

    <p>nature of the ligand</p> Signup and view all the answers

    What is the color observed when V4+ ions are present in aqueous solutions?

    <p>Blue</p> Signup and view all the answers

    Transition metals easily form complex compounds due to their large sizes.

    <p>False</p> Signup and view all the answers

    _________ compounds are formed when small atoms like H, C, or N are trapped inside the crystal lattices of metals.

    <p>Interstitial</p> Signup and view all the answers

    Match the transition metal with its oxidation state: Cu2+

    <p>Copper = Cu2+</p> Signup and view all the answers

    What is the unique feature in the chemistry of lanthanoids related to atomic and ionic radii?

    <p>Lanthanoid contraction</p> Signup and view all the answers

    Which series of elements experiences the consequences of the lanthanoid contraction?

    <p>Third transition series</p> Signup and view all the answers

    Lanthanoid contraction is attributed to the shielding of one electron by another in the same sub-shell.

    <p>True</p> Signup and view all the answers

    Among lanthanoi______s, the shiel______ing of one 4f electron by another is less than one _ electron by another.

    <p>d</p> Signup and view all the answers

    What is the typical range for the first ionization enthalpies of the lanthanoids?

    <p>around 600 kJ/mol</p> Signup and view all the answers

    What is the value of the third ionization enthalpy of lanthanum, gadolinium, and lutetium compared to others?

    <p>abnormally low</p> Signup and view all the answers

    What range do the E values for the half-reaction Ln3+ (aq) + 3e- → Ln(s) fall in for Lanthanoids?

    <p>–2.2 to –2.4 V</p> Signup and view all the answers

    What happens when lanthanoids are heated with hydrogen in gas?

    <p>combine with hydrogen</p> Signup and view all the answers

    What compounds are formed when lanthanoids are heated with halogens or carbon?

    <p>halides or carbides (LnX3, Ln2C3, LnC2)</p> Signup and view all the answers

    What is the oxidation state of chromium in both chromate and dichromate ions?

    <p>6</p> Signup and view all the answers

    Chromate ion, CrO4^2-, has a __________ structure.

    <p>tetrahedral</p> Signup and view all the answers

    Which of the following statements about sodium and potassium dichromates is true?

    <p>Sodium dichromate has greater solubility in water.</p> Signup and view all the answers

    Potassium permanganate is prepared by fusion of MnO2 with an alkali metal hydroxide and an oxidising agent like KNO3.

    <p>True</p> Signup and view all the answers

    Match the following reactions with the oxidized products:

    1. Fe ion to Fe³⁺
    2. Hydrogen sulphide to S
    3. Sulphurous acid to sulphate
    4. Nitrite to nitrate

    <p>Iodine is liberated from potassium iodide = 10I + 2MnO4 + 16H → 2Mn + 8H2O + 5I2 Fe ion (green) is converted to Fe (yellow) = 5Fe + MnO4 + 8H → Mn + 4H2O + 5Fe Oxalate ion or oxalic acid is oxidised at 333 K = 5C2O4 + 2MnO4 + 16H → 2Mn + 8H2O + 10CO2 Hydrogen sulphide is oxidised, sulphur being precipitated = H2S → 2H + S Sulphurous acid or sulphite is oxidised to a sulphate or sulphuric acid = 5SO3 + 2MnO4 + 6H → 2Mn + 3H2O + 5SO4 Nitrite is oxidised to nitrate = 5NO2 + 2MnO4 + 6H → 2Mn + 5NO3 + 3H2O</p> Signup and view all the answers

    Study Notes

    Objectives of the Unit

    • Learn the positions of d-block and f-block elements in the periodic table
    • Understand the electronic configurations of transition (d-block) and inner transition (f-block) elements
    • Appreciate the relative stability of various oxidation states in terms of electrode potential values
    • Describe the preparation, properties, structures, and uses of important compounds like K2Cr2O7 and KMnO4
    • Understand the general characteristics of d-block and f-block elements and their horizontal and group trends

    The d-Block Elements

    • The d-block elements are positioned in the middle section of the periodic table, flanked by s-block and p-block elements
    • The d-block elements are divided into four series: 3d, 4d, 5d, and 6d
    • The general electronic configuration of outer orbitals of d-block elements is (n-1)d ns, except for Pd
    • The d-block elements exhibit characteristic properties like display of a variety of oxidation states, formation of colored ions, and entering into complex formation with ligands

    The f-Block Elements

    • The f-block elements are placed in a separate panel at the bottom of the periodic table
    • The f-block elements are divided into two series: lanthanoids (4f) and actinoids (5f)
    • The electronic configurations of f-block elements are similar to those of d-block elements

    Position of the d-Block Elements in the Periodic Table

    • The d-block elements occupy the large middle section of the periodic table
    • The d-block elements are positioned between s-block and p-block elements

    Electronic Configurations of the d-Block Elements

    • The general electronic configuration of outer orbitals of d-block elements is (n-1)d ns, except for Pd
    • The electronic configurations of d-block elements are given in Table 8.1

    Characteristics of the Transition Elements

    • The transition elements exhibit characteristic properties like display of a variety of oxidation states, formation of colored ions, and entering into complex formation with ligands
    • The transition elements also exhibit catalytic property and paramagnetic behavior
    • The transition elements have high enthalpies of atomization, which are shown in Fig. 8.2
    • The transition elements have high melting points, which are shown in Fig. 8.1

    Physical Properties of the Transition Elements

    • The transition elements display typical metallic properties like high tensile strength, ductility, malleability, high thermal and electrical conductivity, and metallic lustre
    • The lattice structures of transition metals are given in Table 8.2
    • The transition elements have high melting points and boiling points, which are shown in Fig. 8.1
    • The transition elements have high enthalpies of atomization, which are shown in Fig. 8.2### Lanthanoid Contraction
    • Similar to ordinary transition series, lanthanoid contraction is attributed to imperfect shielding of one electron by another in the same set of orbitals.
    • Shielding of one 4f electron by another is less than that of one d electron by another.
    • As nuclear charge increases along the series, there is a regular decrease in the size of the entire 4f orbitals.

    Atomic Radii and Density

    • Atomic radii decrease across the series, resulting in an increase in density due to the increase in atomic mass.
    • Significant increase in density is observed from titanium (Z = 22) to copper (Z = 29).

    Electronic Configurations and Properties

    • Table 8.2 lists the electronic configurations and some properties of the first series of transition elements.
    • The table includes atomic number, electronic configuration, enthalpy of atomisation, ionisation enthalpy, metallic/ionic radii, and standard electrode potential.

    Enthalpy of Atomisation

    • Higher enthalpies of atomisation in transition elements are due to stronger interatomic interaction and bonding between atoms.
    • Zinc has the lowest enthalpy of atomisation, 126 kJ mol-1.

    Ionisation Enthalpies

    • Ionisation enthalpies increase along each series of transition elements due to the increase in nuclear charge.
    • Successive ionisation enthalpies do not increase as steeply as in non-transition elements.
    • Irregular trend in the first ionisation enthalpy of the metals of the 3d series is attributed to the removal of one electron altering the relative energies of 4s and 3d orbitals.

    Oxidation States

    • Transition elements exhibit a great variety of oxidation states, with manganese exhibiting the most (from +2 to +7).
    • The elements that exhibit the greatest number of oxidation states occur in or near the middle of the series.
    • The lesser number of oxidation states at the extreme ends stems from either too few electrons to lose or share or too many d electrons.

    Standard Electrode Potentials

    • Table 8.4 contains the thermochemical parameters related to the transformation of solid metal atoms to M2+ ions in solution.
    • The unique behaviour of Cu, with a positive E°, accounts for its inability to liberate H2 from acids.
    • The general trend towards less negative E° values across the series is related to the general increase in the sum of the first and second ionisation enthalpies.### Element Properties
    • The text provides a table showing the properties of elements Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn, including their Δa H, Δi H, Δ1H2, Δ2H, ΔhydH, and E (M2+/M) values.
    • The table shows varying trends in the E (M3+/M2+) values, reflecting the varying stability of the half-filled d sub-shell in Mn and the completely filled d configuration in Zn.
    • The low value for Sc reflects the stability of Sc with a noble gas configuration.
    • The highest value for Zn is due to the removal of an electron from the stable d configuration of Zn.
    • Table 8.5 shows the stable halides of the 3d series of transition metals.
    • The highest oxidation numbers are achieved in TiX4, VF5, and CrF6.
    • The ability of fluorine to stabilise the highest oxidation state is due to either higher lattice energy or higher bond enthalpy terms for the higher covalent compounds.

    Oxides of 3d Metals

    • Table 8.6 shows the oxides of 3d metals, with the highest oxidation number coinciding with the group number and attained in Sc2O3 to Mn2O7.
    • Oxygen has the ability to stabilise the highest oxidation state, exceeding that of fluorine.

    Chemical Reactivity and E Values

    • Transition metals vary widely in their chemical reactivity, with some being electropositive and dissolving in mineral acids, while others are "noble" and unaffected by single acids.
    • The E values for M2+/M indicate a decreasing tendency to form divalent cations across the series.

    Magnetic Properties

    • The magnetic moment (μ) of an ion is calculated using the "spin-only" formula, μ = √n(n + 2), where n is the number of unpaired electrons.
    • The magnetic moment increases with the increasing number of unpaired electrons.

    Formation of Coloured Ions

    • When an electron from a lower energy d orbital is excited to a higher energy d orbital, the energy of excitation corresponds to the frequency of light absorbed.
    • The colour observed corresponds to the complementary colour of the light absorbed.
    • The frequency of light absorbed is determined by the nature of the ligand, with water molecules as ligands in aqueous solutions.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    Learn about the positions of d-block and f-block elements in the periodic table, including transition metals like iron, copper, silver, and gold.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser