of the element Atomic number Symbol Electronic configuration Einstenium Es [Rn] 5f d s Fermium Fm [Rn] 5f d s Mendelevium Md [Rn] 5f d s Nobelium No [Rn] 5f d s Lawrentium Lr [Rn] 5f s 6d Oxidation state of actinoids: Like lanthanoids, the most common state of actinoids is + . In addition to that actinoids show variable oxidation states such as + , + , + ,+ ,+ and + . The elements Americium(Am) and Thorium (Th) show + oxidation state in some compounds , for example thorium iodide (ThI ). The elements Th , Pa, U ,Np , Pu and Am show + oxidation states.
Np and Pu exhibit + oxidation state. Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + Differences between lanthanoids and actinoids: s.no Lanthanoids Actinoids Differentiating electron enters in 4f orbital Differentiating electron eneters in 5f orbital Binding energy of 4f orbitals are higher Binding energy of 5f orbitals are lower They show less tendency to form complexes They show greater tendency to form complexes Most of the lanthanoids are colourless Most of the actinoids are coloured. For example. U + (red), U + (green) , UO + (yellow) XII U4-D-Block-Jerald XII U4-D-Block-Jerald - - - - s.no Lanthanoids Actinoids They do not form oxo cations They do form oxo cations such as UO NpO , etc Besides + oxidation states lanthanoids show + and + oxidation states in few cases.
Besides + oxidation states actinoids show higher oxidation states such as + , + , + and + . Summary IUPAC defines transition metal as an element whose atom has an incomplete d sub shell or which can give rise to cations with an incomplete d sub shell. They occupy