why are d block elements called transitional metals?Are all d block elements considered as transition metal?Why transitional metals are coloured? for b.sc 2nd year
Answers
Explanation:
Transition metals(d-block) form a bridge between highly active s block metals and low reactive elements of group 13 and 14. Thus they show transitional behaviour between s and p-block and hence are called transition metal.
Not all d-block elements are considered transition metal. Generally transition metals make up group 4 to 11 that most of the d-block. Group 12 belongs to d-block but it is excluded from transition elements.
In the periodic table d blocks elements are placed between the highly electro positive s block elements and highly electronegative p block elements.
This is why they are called d block elements.
Transition elements may be defined as those elements which posses partly filled d orbitals in their elementary form or in their ions existing significant oxidation states.
Expect Cu and Zn , all other elements have partly filled d orbitals in their elementary forms and are true transition elements.
Conclusion : it may be concluded that the end members of the transition series, i.e Zn,Cd and Hg are not transition elements in true sense because they possess completely filled d orbitals in their elementary forms.
The colour in transition metal ions is due to d-d transition taking place between the splitted d orbitals .The transition metal ions having completely filled d orbitals r empty d orbitals are colourless.