How to form a complex?

Answer 1

A complex is made up of a central metal atom/ion surrounded by negatively charged ions or neutral molecules possessing a lone pair of electrons (ligands). A complex may be charged or uncharged, if it is charged it is called a complex ion, for example [Fe(H2O)6]3+. The overall charge is the sum of the charge on the central metal ion and the charges on the ligands. A simple way of looking at the bonding in a complex, is looking at the bonds as being co-ordinating bonds from the ligands (i.e. the ligands give up their pair of electrons to form a dative bond). The co-ordination number is the number of co-ordinating (dative) bonds to the central metal ion; the most common co-ordination numbers are 6 and 4. The shape of the complex is determined by the co-ordination number: Most complexes form the shapes above; however, there are some exceptions, for example in the [Cu(H2O)6]2+ Ion, four of the water ligands are held more strongly than the other two; this results in a distorted tetrahedral shape.