Transition Elements Flashcards
Why can transition elements exhibit a variety of oxidation states
Due to close proximity in energy of the 3d and 4s electrons. Thus both are available for bond formation
Why can transition elements act as homogeneous catalysts
Homogeneous catalysts are catalysts with the same state as the reactants. Since transition elements have variable oxidation states, they are able to transfer electrons and vary oxidation states easily to form reaction intermediates. An alternative pathway with lower activation energy is created, to increase rate of reaction.
Why can transition elements act as homogeneous catalysts
Homogeneous catalysts are catalysts with the same state as the reactants. Since transition elements have variable oxidation states, they are able to transfer electrons and vary oxidation states easily to form reaction intermediates. An alternative pathway with lower activation energy is created, to increase rate of reaction.
Why can transition elements act as heterogeneous catalysts
Heterogeneous catalysts are catalysts that have different states from the reactants . They provide the surface in which adsorption of reactant molecules Ike’s and desorption of product molecules take place. Transition elements have partially filled d-subshells that allow for adsorption of reactant molecules and vacant d orbitals can act as electron acceptors from reactant molecules and d electrons can act as electron donors to reactant molecules
Why are transition elements coloured
In a gas-phase free metal ion, the d orbitals are degenerate. In the presence of ligands, the 5 d orbitals are split into two energy levels (with an energy gap deltaE) due to reputation between the metal ion and the ligands. The energy gap, deltaE, between the non-degenerate orbitals corresponds to the wavelength of light in the visible region of the electromagnetic spectrum.
For a transition metal ion with partially filled d-orbitals, when a d-electron from a lower energy group is promoted to the higher energy group (d-d transition) radiation in the visible region of the electromagnetic spectrum corresponding to deltaE is absorbed. Light energy what is not absorbed will be seen as the colour of the complex.
Explain the splitting of degenerate d orbitals in an octahedral complex
In an octahedral complex, the d subshell is of higher energy level than in gas phase ion due to the repulsion of the electrons in the d orbitals by the lone pair of electrons on the ligands. dz^2 and dx^2y^2 orbitals experience stronger electronic repulsion as the orbital lobes are on the axes that are in line with the approach of the ligands, while the dxy, dyz, and dxz orbitals have lobes that project between the axes. Due to stronger electronic repulsion, the dz^2 and dx^2y^2 orbitals are at a higher energy level and the degenerate d orbitals split into two different energy levels.
