Question

Which is the correct order of ionization energies of the coinage metals.

• A. Cu > Ag < Au
• B. Cu > Ag > Au
• C. Cu < Ag < Au
• D. Au > Ag < Cu

Answer 1

The correct option is A

Cu > Ag < Au

Cu - 3$d^{10}$ 4$s^1$; Ag - 4$d^{10}$ 5$s^1$, Au - 4$f^{14}$ 5$d^{10}$ 6$s^1$
In Cu, Ag, Au unpaired s electron has to be removed
In Cu 4s electron has to removed while is Ag 5s, so I.E of Cu > Ag.
In Au due to improper screening effect of 14 electrons of 4f orbitals, the nucelar charge increases and therefore 6s electrons of Au are more tightly held than 5s electrons of Ag.