PF1009 2024 5 d-Block Metals PDF

Pharmaceutical Chemistry d-Block Elements Dr. J.J. Keating 1  d-Block Elements 30 elements. Can form numerous complexes. Widely used as catalysts. Extensive range of oxidation numbers. 1...

Pharmaceutical Chemistry d-Block Elements Dr. J.J. Keating 1  d-Block Elements 30 elements. Can form numerous complexes. Widely used as catalysts. Extensive range of oxidation numbers. 1 2 3 4 5 6 7 8 9 10 Period 4 1st Row Period 5 2nd Row Period 6 3rd Row 2 Multi-Vitamin Preparations – d-Block Elements % EU RDA = European Union Recommended Daily Amount = amount of each element in each tablet as a percentage of the recommended daily intake of the element. O Fe2+  C4H2FeO4  O O O ZnO ferrous fumarate MnSO4 CuSO4 CrCl3 Na2MoO4 3  Infant Formula – d-Block Elements K+ O Ca3(PO4)2  O O HO K+ K3C6H5O7   O O K+ O NaCl potassium MgCl2 citrate KCl FeSO4 ZnSO4 CuSO4 KI KOH Na2SeO4 4  d-Block Elements The members of the d-block, which are also widely called the transition metals, are the workhorse elements of the periodic table: Construction metals – Fe, Cu Metals in new technologies – Ti (aerospace), V (catalysts) Precious metals – Ag, Pt, Au Pharmaceuticals – V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ag, Au, Tc, Pt d-block metals – so called as its members have electron configurations where the d- orbitals are being occupied. In the d-block atoms, the d-electrons are bound more strongly than the valence s- electrons. When a d-block atom becomes a cation, the valence s-electrons are lost first, after which a variable number of d-electrons may be lost: Fe (iron) – [Ar]3d64s2 26 Fe2+ (Fe(II), ferrous) – [Ar]3d6 Fe3+ (Fe(III), ferric) – [Ar]3d5 5  d-Block Elements As there are 5 d-orbitals in a given sublevel in a given shell, and each can accommodate up to 2 electrons, there are 10 elements in each row of the d-block. All d-block elements are metals. Au is the best electrical conductor. 79 They are usually malleable, ductile, lustrous, silver-white and have relatively high mp’s and bp’s. Exceptions: 80Hg – liquid at rt; 29Cu – red-brown; 79Au – yellow. Hg 80 Cu 29 Au 79 43Tc mercury copper gold technetium 6  d-Block Elements – Oxidation Numbers Except for 80Hg, the elements at the ends of each row of the d-block have only one ox. no. other than 0 (30Zn, 48Cd) 21Sc – only +3; 30Zn – only +2 Elements close to the centre of each row – widest range of ox. No., especially 25Mn (7 ox. states) Elements towards the left, and in the 2nd and 3rd rows – more likely to form compounds with higher ox. no. 24Cr atom of CrO4 2– (ox. +6) easily reduced, whereas 74W of WO42– (ox. +6) quite stable. Oxidation numbers help to rationalise the properties of d-block compounds. 25Mn in the form of MnO4 (ox. no. +7) – good oxidising agent: – MnO4– + 5H+ + 5e– → Mn2+ + 4H2O KMnO4 7  d-Block Elements – Atomic Radii Decrease from Sc to Ni, as the increasing nuclear charge and poor shielding of the d- electrons. A 3d64s2 26Fe atom (atomic radius 126 pm) is smaller than a 3d14s2 21Sc atom (160 pm) even though Fe has more d-electrons. Atomic radii of elements in the third row are about the same as those in the second row – lanthanide contraction. 1 pm (picometer) = 10–12 m. Row 1 (Period 4) (21 – 30) Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn Row 2 (Period 5) (39 – 48) 5th 6th 7th Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd Row 3 (Period 6) (71 – 80) Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg 8  d-Block Elements – Densities Period 6 have relatively high densities. 76Os (22.61 g/cm3, Row 3 (Period 6), 6th element), 77Ir (22.65 g/cm3,Row 3 (Period 6), 7th element). Period 6 atomic radii are comparable to those of elements in Period 5, whereas their atomic masses are about twice as large. 9 d-Block Elements – Densities 10  d-Block Elements – First Ionisation Energies Minimum energy required to remove the most loosely bound electron from an atom in a mole of gaseous atoms, measured in kJ.mol–1. As the nuclear charge increases from left to right across the table, the first ionisation energies also increase (632 kJ.mol–1 (21Sc), 762 kJ.mol–1 (26Fe)). 2nd and 3rd row elements – same general trend in atomic radii and ionisation energies. 11