A transitional element is a d block element that forms at least one ion with an incomplete d sub-shell.
the d-block elements would have filled their 4s orbitals before their 3d orbitals( the 4s sub-shell has a lower energy than the 3d sub-shell ).
chromium which is a transition metal has its 3d and 4s orbitals half-filled(4s1 3d5)
copper only one electron is in the 4s orbital but the 3d orbital is full
To form positive ions transition element atoms loose electrons from their 4s sub-shell before their 3d subshell.
Properties specific to transition metal compounds in result to of their electron configuration(partially filled d-orbitals):
exist as giant metallic lattices containing delocalised electrons which move to conduct electricity
shiny in appearance
catalyse chemical reactions
high density and melting point and boiling point
form coloured compounds
form compounds in which they have different oxidation states
transition metals from titanium to copper don't form the +2 oxidation state
KMnO4 is a purple solid used as a oxidising agent in redox titrations
important chemical reactions that are catalysed by transition metals or their compounds
Hydrogenation of alkenes
Decomposition of hydrogen peroxide
All ligands are neutral