Iron is widely used in biological redox systems in which both the +2 and +3 oxidation…
CHEMISTRY · Multi-part · AP · Chemistry · Atomic Structure and Properties · Atomic Structure and Properties
Problem
Iron is widely used in biological redox systems in which both the +2 and +3 oxidation states play important roles.
Answer the following questions about the electronic structure of neutral iron and its common cations.
(a) Write the complete ground-state electron configuration of a neutral Fe atom (atomic number 26) using the bracket-notation format that begins with [Ar].
(b) Determine the complete electron configurations of the ions Fe2+ and Fe3+. Clearly indicate which electrons are removed when the atom is oxidized from the neutral state to each cationic state.
(c) The first two electrons removed from a gaseous Fe atom come from the 4s subshell rather than the 3d subshell even though the 4s subshell is occupied first in the neutral atom. Explain this observation in terms of relative subshell energies before and after ionization.
(d) Using Coulombic arguments and the concept of effective nuclear charge, predict which of the species Fe, Fe2+, or Fe3+ has the highest first-ionization energy and justify your answer.