Chemistry - Complete d-block Question with Solution | TestHub

The IUPAC definition of a transition element is that it is an element that has an incomplete d-subshell in either the neutral atom or its ion. Thus the group 12 elements are member of the d-block but are not transition elements.

Chemically soft members of the d-block occurs as sulphide minerals and are partially oxidised to obtain the metal, the more electropositive 'hard' metals occurs as oxides and are extracted by reduction.

Opposite to p-block tend to exist in low oxidation states and favoured by the heavier elements of d-block. Metals on the right of the d-block tend to exist in low oxidation states and form complexes with the ligands. Square-planar complexes are common for the platinum metals and gold in oxidation state that yield d⁸ electronic condiguration, which include Rh (I), Ir(I), Pd(II), Pt(II) and Au(III). 

The most distinctive features/properties of transition metal complex is their wide range of colours. The crystal field theory attributes the colour of the coordination compounds to d-d transition of the electron. It is important to note that (a) in absence of ligand, crystal field splitting does not occur and hence the substance is colourless ; (b) the type of ligand also influences the colour of the complexes.