(a) Answer the following questions :
(i) Which element of the first transition series has highest second ionization enthalpy?
(ii) Which element of the first transition series has highest third ionization enthalpy?
(iii) Which element of the first transition series has lowest enthalpy of atomisation?
(b) Identify the metal and justify your answer.
(i) Carbonyl M (CO)5
(ii) MO3F
(i) Copper has electronic configuration [Ar] 3d10 4s1. Removing the loosely bound 4s electron is easier but removing a second electron from a completely filled d orbital is harder. So, the second ionization enthalpy will be the highest for Cu.
(ii) Zinc has electronic configuration [Ar]3d10 4s2. Removing the two 4s electrons will be easier but removing the third electron from completely filled d orbital will be harder. Therefore, zinc has the highest third ionization enthalpy
(iii) Zinc will have the lowest enthalpy of atomization because it has no unpaired electrons for metallic bonding.
(b)
(i) The metal M is Fe
(ii) The oxidation state of M is +7 and only Mn shows +7 oxidation state. D-electrons are not involved in bonding.