Periodic table+ general periodicity CAQ

🌈 Periodic table Created Tags Halogens State and explain the relative thermal stability of hydrogen halides Thermal stability decreases down the group 17 As HX bond energy decreases as less effective orbital overlapping between orbitals of H atom and halogen atom as size of halogen atom increases resulting in longer and weaker HX bond Hence less energy to break the HX bond decreases HCl does not decompose even on strong heating. 0.5 HBr yields reddish-brown (accept “brownˮ) fumes of Br2 under strong heating. 0.5 HI gives violet fumes of I2 when red‐hot rod is plunged into jar of HI. 0.5 Trend in volatility down the group they have simple molecular structures with weak Iʼd-Iʼd between molecules Down the group, electron cloud size of halogen molecules increases and becomes more easily polarised, leading to stronger London dispersion forces, more energy to overcome the stronger Iʼd-Iʼd, bp increases and volatility decreases June 8 , 2025 119 AM P er iodic t able 1

Transition metal Definitions: Transition metals are d block elements which form one or more stable ions with a partially filled d subshell Ligand: an ion or molecule that contains at least one atom bearing a lone pair of electrons which can be donated into a low-lying vacant orbital of a central metal cation, forming a dative covalent bond A complex contains a central metal cation, bonded ligands by dative covalent bonds Why is copper/ any metal in d block element transition metals? it is a d-block element which forms one or more stable ions with a partially filled d-subshell Questions regarding properties of transition metals Physical properties: Property Explanation Higher mp/mp than non-transition metals transition metal can contribute the3d and 4s electrons for metallic bonding while non- transition metal can only contribute the 4s electrons for metallic bonding. The metallic bond is stronger for transition metal, and hence it has a higher melting and boiling point Higher density Density = mass/volume. Transition metals has a heavier relative atomic mass than non-tm, tm have a smaller atomic radius than non-tm .Hence, there are more tm atoms per unit volume than in non-tm and hence P er iodic t able 2

Property Explanation densities of tm is significantly greater than that of non-tm Similar atomic radii across the period Across the transition elements series, nuclear charge increases and electrons are addedto the inner principal quantum shell 3d subshell). Shielding effect for valence shell 4selectrons increases due to the increase in no. of inner shell (3d) electrons. Nuclearattraction for the valence electrons is almost constant, hence the atomic radii are relativelysimilar. Chemical properties: Properties Explanation Transition metals less reactive Less likely to undergo oxidation unlike group 1 and 2 metals, compare E values Exhibit variable oxidation states Transition elements exhibit variable oxidation states in their compounds due to the close similarity in energy of the 3d and 4s orbitals. Hence, both 3d and 4s electrons can be removed to form stable ions of different oxidation states. why is aqueous transition metal ions such as Cu2+ are coloured while zn2+ is colurless/ why certain transition metal ions produce colour less solutions P er iodic t able 3

In the presence of H2O ligands, repulsion between the lone pair electrons of ligands and the d orbital electrons causes the degenerate d-orbitals of the Cu2 ion are split into two different energy levels with a small energy gap, ΔE. As 3d Su shell is partially filled, Electrons in the lower energy d-orbitals can absorb light of a certain wavelength with energy corresponding to the energy gap, ΔE, and be promoted to the higher energy d-orbitals (d-d transition). The colour of the complex is the complementary colour of the wavelength absorbed. For Zn2+(aq), the 3d orbitals are fully filled with 3d10 configuration. The is no d-d transition and all the light are transmitted and Zn2+(aq) appears colourless Look at the electronic configuration: Has a empty d sub shell/ fully filled d subshell, no d-d transition, no light absorbed and appears colourless Note: when question says aqueous ions it means that the ligand is H2O Why do different complex ions have different colours? Different ligands: The ligands are different in the two compounds, resulting in a different degree of replusion between the lone pair electrons of the ligands and d orbital electrons of transition metal ion The degenerate 3d orbitals are split into 2 different energy levels with an energy gap and the energy gap is is different for the two compounds. In each case, electrons in the lower energy 3d orbitals absorb visible light of a certain wavelength with energy correspond to energy gap as they get promoted to the higher energy d orbitals. Different wavelength of light is absorbed and hence we observed a different complemantary colour. Different overall charge: P er iodic t able 4

As overall charges of complex ions are different, The number of d electrons are different, resulting in a different degree of replusion between the lone pair electrons of the ligands and d orbital electrons The degenerate 3d orbitals are split into 2 different energy levels with an energy gap, and energy gap is different for the two compounds. In each case, electrons in the lower energy 3d orbitals absorb visible light of a certain wavelength with energy correspond to energy gap as they get promoted to the higher energy d orbitals. Different wavelength of light is absorbed and hence we observed a different complementary colour. Why is carbon monoxide poisonous? Binds more strongly than oxygen with iron ion in haemoglobin to form very stable complexes, cutting down the supply of oxygen to the body Why are transition metal ions able to form variable oxidation states unlike group 1 and 2 metals Due to the close similarity in energy of the 3d and 4s orbitals ,different numbers of) 3d and 4s electrons can be removed to form stable ions of different oxidation states. However, once the valence electrons from s orbitals of group 1 and 2 are removed, the subsequent electrons removed must come from the next inner quantum shell which required large additional amount of energy and hence, does not have variable oxidation states. Cis trans isomerism in complexes P er iodic t able 5

For cis isomerism, the same atoms must face the same direction of the plane Drawing 3D diagram for complex Need to show the 3d lines Why is there different number of ligands surrounding the same central atom in different complexes Electron cloud of the ligand larger than the other ligand, less of that ligand can be placed around central atom or ion in a complex ion Reaction of Cu complex with reagents Dilute sulfuric acid Observation: blue solid dissolves in sulfuric acid to give a pale blue solution containing [Cu(H2O)62 Type of reaction: acid base reaction Equation: Cu(H2O)4OH2  H2SO4  [Cu(H2O)6SO4 or Cu(H2O)4OH2 + H2SO4  CuSO4  6H2O (depends on context of question) P er iodic t able 6

Excess ammonia Observation: blue solid dissolves in excess to give a deep blue solution containing [Cu(NH3)4H2O22 or [Cu(NH3)42 Type of reaction: Ligand exchange reaction Equation: Cu(H2O)4OH2  4NH3 [Cu(NH3)4H2O22  2OH  2H2O Or Cu(H2O)4OH2  4NH3 [Cu(NH3)42  2OH  4H2O Concentrated HCl Observation: Blue solid dissolves in excess to give a yellow solution of CuCl42 Type of reaction: Ligand exchange reaction Equation: Cu(H2O)4OH2  4Cl− CuCl42  2OH  4H2O Explain how some transition metal can act as catalyst have ions of variable oxidation states, allowing it to function as a homogenous catalyst Have partially filled d subshell allowing it to accept electrons from reactants and act as a heterogeneous catalyst How are compounds containing copper (II) ions different and similar to Mg ions in terms of chemical behaviour D