Transition Metal Electronic Configurations and Complexes

Flashcards on Transition Metal Chemistry

Transition Metals

D-block elements that form one or more stable ions with incompletely filled d-orbitals.

Characteristics of Transition Metals

Hard solids, high melting and boiling points, act as catalysts, form colored ions and compounds, form ions with different oxidation numbers, and form ions with incomplete d-blocks.

Electronic Configuration Filling Order

The 4s subshell is filled before the 3d subshell.

Exceptions to Electronic Configuration Filling

Chromium and copper do not follow the expected filling pattern for added stability.

Ion Formation in Transition Metals

Elements lose 4s electrons before 3d electrons when forming ions.

Oxidation Numbers in Transition Metals

Elements can form ions with different oxidation numbers, with higher numbers often found with electronegative elements like oxygen.

Complex

A central metal or ion surrounded by ligands.

Ligand

A molecule or ion that forms a dative (coordinate) bond with a transition metal, donating a pair of electrons.

Coordination Number

The number of coordinate bonds to the central metal or ion.

Monodentate Ligand

Ligands that can form only one coordinate bond to a metal ion, as they have one lone pair to form one coordinate bond (e.g., H2O, NH3, Cl-).

Octahedral Complex

Complexes commonly formed by transition metal ions with small ligands, bonds at 90° (e.g., H2O and NH3).

Tetrahedral Complex

Complexes commonly formed by transition metal ions with larger ligands, bonds at 109.5° (e.g., Cl-).

Square Planar Complex

Complexes such as xenon tetrafluoride (XeF4) and cis-platin; can display cis-trans isomerism.

Bidentate Ligand

Ligands that can form two coordinate bonds to a metal ion (e.g., ethanedioate ion, ethane-1,2-diamine).

Multidentate Ligand

Ligands that can form many coordinate bonds to a metal ion (e.g., EDTA4-).

Ligand Substitution Reaction

In a complex, one ligand can be replaced by another.

Chelate Effect

Bidentate and multidentate ligands replace monodentate ligands form complexes much more readily than replacing monodentate with monodentate.

Haemoglobin

A protein in red blood cells that contains an iron(II) complex with a multidentate ligand and is involved in reversible oxygen binding.

Carboxyhaemoglobin

A very stable complex formed when carbon monoxide replaces oxygen in haemoglobin, preventing oxygen transport.

Colour Absorption in Transition Metals

Arises when some wavelengths of visible (white) light are absorbed due to incomplete d shell.

Factors Affecting Color in Complexes

Changes in oxidation state, coordination number, or the ligand will alter ΔE and so the colour observed will change.