the central position of the periodic table, between s and p block elements, d- Block elements composed of 3d series (4th period) Scandium to Zinc ( elements), 4d series ( th period) Yttrium to Cadmium ( elements) and 5d series ( th period) Lanthanum, Haffinium to mercury. The general electronic configuration of d- block elements can be written as Noble gas n d ns , Here, n = to . In periods and , the configuration includes ( n f orbital ; [ Noble gas n f n d ns . All the transition elements are metals.
Similar to all metals the transition metals are good conductors of heat and electricity. Unlike the metals of Group- and group- , all the transition metals except group elements are hard. As we move from left to right along the transition metal series, melting point first increases as the number of unpaired d electrons available for metallic bonding increases, reach a maximum value and then decreases, as the d electrons pair up and become less available for bonding. Ionization energy of transition element is intermediate between those of s and p block elements.
As we move from left to right in a transition metal series, the ionization enthalpy increases as expected. The first transition metal Scandium exhibits only + oxidation state, but all other transition elements exhibit variable oxidation states by loosing electrons from (n- )d orbital and ns orbital as the energy difference between them is very small. In 3d series as we move from Ti to Zn, the standard reduction potential E M M + value is approaching towards less negative value and copper has a positive reduction potential. i.e., elemental copper is more stable than Cu + .
XII U4-D-Block-Jerald XII U4-D-Block-Jerald - - - - Most of the compounds of transition elements are paramagnetic. Magnetic properties are related to the electronic configuration of atoms. Many industrial processes use transition metals or their compounds as catalysts. Transition metal