University:
York University
Course:
CHEM 1001 | Chemical Dynamics
Academic year:

2022
Views:

167

Pages:

2
Author:

Niklas

Precipitation Reactions Hard water: found in ground and well water, contains dissolved metal ions (Ca²⁺, Mg²⁺). Adding anions and cations to a solution can cause sparingly soluble compounds to precipitate. Used in qualitative analysis to identify metal ions in solutions. Amphoteric Metal Oxides and Hydroxides Amphoteric hydroxides: Al, Cr, Zn, Sn, and many transition metal ions. Dissolution involves the formation of complex ions. Both low and high pHs increase their solubility. Complexation Lewis acid and Lewis base interaction is stronger than intramolecular bonds. Transition metals are Lewis acids. Ligands are Lewis bases. Common ligands: H₂O, NH₃, Cl⁻, CN⁻, SCN⁻, OH⁻, oxalate, EDTA⁴⁻. Equilibrium constants for complex formation. Complexes typically contain 2 or more ligands. Complexation Terminology Na₃[Fe(CN)₆] Coordination number: number of ligating groups on the central metal ion. Dictated by bonding preferences of the metal ion, its oxidation state, and the identity of surrounding ligands. Coordination Numbers Most common coordination numbers: 2, 4, 6. Some metals prefer 2 (Cu, Ag, Au). As ligands get larger, fewer can surround the metal. Ligands that transfer substantial negative charge to the metal can also have lower coordination numbers. Complex Geometry Affects physical and chemical properties. Stereoisomers: 2 different geometries for square planar and octahedral. "cis" and "trans" isomers. Stereoisomers Geometric isomers: atoms or groups of atoms are arranged differently in space. Optical isomers: mirror images of each other that are not superimposable. A Closer Look at Ligands Monodentate ligands: bind to the metal ion through one atom. Bidentate ligands: bind to the metal ion through two atoms. Example: ethylenediamine