Brief Summary
This comprehensive mind map of the d- and f-block elements covers electronic configurations, periodic properties, important compounds, and key concepts. It explains transition elements, lanthanoid contraction, oxidation states, magnetic properties, and catalytic behavior. The video also provides memory tricks, and detailed explanations of chemical reactions.
- Electronic Configuration and Properties
- Key Compounds and Reactions
- F-Block Elements and Transuranium Elements
Introduction
The video introduces a mind map series for Class 12 Chemistry, focusing on the d- and f-block elements. The presenter aims to provide a fast-paced overview of the chapter, covering all essential topics.
Topics to be covered
The session will cover introduction, electronic configuration, periodic properties, compounds of d-block elements, f-block elements, and their periodic properties.
Periodic table of the elements
D-block elements are located between the s- and p-blocks in the periodic table, specifically in groups 3 to 12. They are also known as transition elements, though not all d-block elements fit this definition.
Tramsition Metal
Transition elements are defined as d-block elements with incompletely filled d orbitals in their ground state or most stable oxidation states. Zinc (Zn), Cadmium (Cd), and Mercury (Hg) are not considered transition elements because they have completely filled d orbitals (d¹⁰ configuration) in both their ground state and stable oxidation states. Copper (Cu), Silver (Ag), and Gold (Au) are considered transition elements because they can form ions with incomplete d orbitals.
Electronic Configuration
The general electronic configuration for d-block elements is (n-1)d¹⁻¹⁰ ns¹⁻². There are four series: 3d, 4d, 5d, and 6d. The 3d series includes elements from Scandium (Sc) to Zinc (Zn). Exceptions to the filling order occur in Chromium (Cr) and Copper (Cu) to achieve half-filled or fully filled d orbitals, which increases stability. Memory tricks are provided to remember the series. A trick is shared for writing electronic configurations of 4d and 5d series elements, involving exceptions and serial numbering. When forming ions, electrons are always removed from the outermost shell first.
Physical Properties
D-block elements are metals and exhibit typical metallic properties such as high tensile strength, ductility, malleability, thermal and electrical conductivity, and metallic luster. Most transition elements are hard and have low volatility, except for Zn, Cd, Hg, and Hg is liquid at room temperature.
Atomic Size
Atomic radius is defined as the distance from the center of the nucleus to the outermost electron. The size is affected by attractive and repulsive forces. From Scandium to Manganese, the atomic radius decreases due to increasing nuclear charge. From Iron to Nickel, the atomic radius remains relatively constant. From Copper to Zinc, the atomic radius increases due to increased electron-electron repulsion.
Lanthanoid Contraction
Lanthanoid contraction results in the radii of 4d and 5d series elements being similar. This is due to the poor shielding effect of f-electrons. The 5d series elements experience a greater effective nuclear charge, causing their radii to contract and become similar to those of the 4d series elements.
Density
Density is mass per unit volume. From Scandium to Copper, density increases. In a group, density increases from 3d to 5d. The density of 5d series elements is higher than that of 4d series elements due to lanthanoid contraction.
Metallic Character
Metallic character depends on the number of unpaired electrons available for metallic bonding. Metals are electron donors and exist as M+ ions in a metallic lattice surrounded by electrons. The strength of the metallic bond is directly proportional to the number of unpaired electrons. Up to Chromium, metallic character increases, then decreases.
Melting & Boiling Point
Melting and boiling points are directly proportional to the strength of the metallic bond, which depends on the number of unpaired electrons. Melting point increases up to Chromium and then decreases. Manganese shows a dip in melting point due to its stable half-filled d⁵ configuration, which reduces its tendency to participate in metallic bonding.
Enthalpy Of Atomisation
Enthalpy of atomization is the energy required to convert a metal from its solid state to an isolated gaseous state. It is directly proportional to the metallic bond strength and the number of unpaired electrons.
Ionisation Enthalpies
Ionization energy generally increases from left to right across the d-block series. Zinc has the highest first ionization energy. Mercury (Hg) has a higher ionization energy than Cadmium (Cd) due to the poor shielding of f-electrons in Hg.
Oxidation State
Transition elements exhibit variable oxidation states due to the small energy difference between the 3d and 4s orbitals. Scandium and Zinc do not exhibit variable oxidation states. The maximum oxidation state increases up to Manganese and then decreases. Stable oxidation states correspond to noble gas configurations, half-filled d orbitals (d⁵), fully filled d orbitals (d¹⁰), or half-filled t₂g orbitals (d³). Chromium (+3) is stable due to its t₂g³ configuration, and Manganese (+2) is stable due to its d⁵ configuration. Iron exhibits +2 and +3 oxidation states, with +3 being more stable due to its half-filled d⁵ configuration. The stability of higher oxidation states increases down a group. For example, Cr(VI) is an oxidizing agent because it is unstable and readily reduces to Cr(III).
M2+ / M Standard Electrode Potentials
The standard electrode potential (E°) is calculated from the sum of enthalpy of atomization, ionization energy, and hydration energy. A negative E° value indicates that the M²⁺ ion is not interested in reduction, while a positive value indicates it is. Copper has a positive E° value, which accounts for its inability to liberate H₂ from acids. The high second ionization energy of copper is not balanced by its hydration energy, leading to its positive E° value. Manganese has a more negative E° than expected due to the stability of its half-filled d⁵ configuration.
M3+ / M2+ Standard Electrode Potentials
Scandium has a very negative E° value because Sc³⁺ is highly stable due to its noble gas configuration. Manganese has a positive E° value because Mn³⁺ is unstable and readily reduces to Mn²⁺, which has a stable half-filled d⁵ configuration.
Stability Of Higher Oxidation States
Transition metals stabilize higher oxidation states with oxygen and fluorine due to the high lattice energy or bond enthalpy of their compounds. Fluorine's ability to stabilize higher oxidation states is due to its small size and high electronegativity. Oxygen stabilizes higher oxidation states by forming multiple bonds. MnF₇ is not stable due to steric crowding. CuI₂ does not exist because Cu²⁺ oxidizes I⁻ to I₂, reducing itself to Cu⁺. Copper (+2) is more stable than Copper (+1) in aqueous solution due to its higher hydration energy.
Magnetic Properties
Substances are classified as diamagnetic (repelled by a magnetic field), paramagnetic (attracted to a magnetic field), or ferromagnetic (strongly attracted). Diamagnetic substances have no unpaired electrons (n=0), while paramagnetic substances have unpaired electrons (n≠0). The magnetic moment (µ) is calculated using the formula µ = √n(n+2) BM, where n is the number of unpaired electrons.
Formation Of Coloured Ions
If a compound has unpaired electrons (n ≠ 0), it is colored; if it has no unpaired electrons (n = 0), it is colorless. MnO₄⁻ is purple and Cr₂O₇²⁻ is orange due to charge transfer (CT) from oxygen to the metal.
Formation Of Complex Compounds
D-block elements form complex compounds due to the availability of vacant d-orbitals, small size, and high ionic charge.
Catalytic Properties
D-block elements exhibit catalytic properties due to their ability to show variable oxidation states and form complex compounds. Catalysts provide a surface for reactions and lower activation energy. Examples include V₂O₅ in the Contact Process, Fe₂O₃ in the Haber Process, and Pt/Rh in the Ostwald Process.
Formation Of Interstitial Compounds
Interstitial compounds are formed when small atoms like carbon, hydrogen, and nitrogen are trapped inside the lattice structure of metals. These compounds have high melting points, are very hard, retain metallic conductivity, and are chemically inert.
Alloy Formation
Alloys are formed by mixing two or more metals or a metal and a non-metal in a molten state, followed by cooling. Alloys are formed by elements with metallic radii within 15% of each other. D-block elements form many alloys due to their similar radii.
Important compounds of transition elements
Metal oxides are generally basic, but their nature depends on the oxidation state of the metal. Oxides with +1, +2, or +3 oxidation states are basic; +4 oxides are amphoteric; and +5, +6, or +7 oxides are acidic. A trick is provided to remember amphoteric oxides.
Potassium dichromate K2Cr2O7
Potassium dichromate (K₂Cr₂O₇) is derived from chromate ore (FeCr₂O₄). The process involves converting chromite ore to sodium chromate, then to sodium dichromate, and finally to potassium dichromate. Dichromate and chromate ions are interconvertible depending on pH. In acidic solution, dichromate is an oxidizing agent and is reduced from +6 to +3.
Potassium Permanganate KMnO4
Potassium permanganate (KMnO₄) is derived from pyrolusite ore (MnO₂). The process involves converting MnO₂ to manganate ion (MnO₄²⁻), then to permanganate ion (MnO₄⁻). KMnO₄ can be produced via chemical or electrolytic oxidation. The structure of MnO₄⁻ is tetrahedral.
F Block Elements
F-block elements include the lanthanides and actinides. Memory tricks are provided to remember the series. The general electronic configuration is provided, and a trick is shared for writing electronic configurations.
Atomic And Ionix Sizes
Atomic radius decreases from left to right across the lanthanide series. Europium has the maximum radius. Ionic radius decreases with increasing atomic number. Lanthanides commonly exhibit a +3 oxidation state. Cerium (+4) is an oxidizing agent, while Europium (+2) and Ytterbium (+2) are reducing agents.
Thank You
Actinides also commonly exhibit a +3 oxidation state. The video concludes with a discussion of transuranium elements, which are elements with atomic numbers greater than 92 (Uranium).
