Chapter 19 Transition Metals and Coordination Chemistry19.1 The Transition Metals: A Survey19.2 The First-Row Transition Metals19.3 Coordination Compounds19.4 Isomerism19.5 Bonding in Complex Ions: The Localized Electron Model19.6 The Crystal Field Model19.7 The Molecular Orbitials circuit breakout19.8 The Biological Importance of Coordination Complexes
The transition metals show great similarities within a given period as well as within a given vertical group.The last electrons added to the transition metal elements are inner electrons: d electrons for the d-block transition metaland felectrons for the lanthanide and actinides.These inner dand felectrons cannot participate in bonding as readily as the valences sand pelectrons can.Thus the chemistry of the transition metals is not as greatly affected by the gradual change in the number of electrons as in the chemistry of the representative group.General propertiesGeneral properties
The transition metals behave as typical metals, exhibiting metallic luster and relatively high electrical and thermal conductivity.Silver (Ag) is the best conductor of heat and electrical current. However, copper (Cu) is a close second, which explains copper’s wide use in the electrical systems of homes and factories.Tungsten (W) with a melting point of 3400 oC is used for filaments in light bulbs; in contrast, mercury (Hg) is a liquid at 25 oC.
Some transition metals like iron (Fe) and titanium (Ti) are hard and strong and therefore make very useful structural materials; in contrast, copper (Cu), gold (Au) and silver (Ag) are relatively soft.Chromium (Cr), nickel (Ni) and cobalt (Co) form oxides that adhere tightly to the metallic surface, thereby protecting the metal form further oxidation.Iron (Fe) forms oxides that scale off, constantly exposing new metal to the corrosion process.The noble metals like gold (Au), silver (Ag), platinum (Pt), and palladium (Pd) do not readily form oxides.
Forming ionic compounds with nonmetalsForming ionic compounds with nonmetalsMore than one oxidation state is often found. For example, iron combines with chlorine to form FeCl2and FeCl3.The cation are often complex ions, in which the transition metal ion is surrounded by a certain number of ligands. [Co(NH3)6]Cl3
Co2+Mn2+Cr3+Fe3+Ni2+Most compounds are colored, because the typical transition metal ions in a complex can absorb visible light of specific wavelengths.Most of compounds are paramagnetic (they contain unpaired electrons).
Calcite stalactites colored by ironQuartz is often colored by the Mn, Fe and Ni transition metalsWurfenite contains PbMoO4Rhodochrosite contains MnCO3
Electron ConfigurationsElectron ConfigurationsThe 3d orbitals begin to fill after the 4s orbital is completed that is after calcium [Ar]4s2.