Question

Write down the number of 3d electrons in each of the following ions: Ti2+, V2+, Cr3+, Mn2+, Fe2+, Fe3+, CO2+, Ni2+ and Cu2+ . Indicate how would you expect the five 3d orbitals to be occupied for these hydrated ions (octahedral).

Answer 1

Metal ion	Numbers of d-electrons	Filling of d-orbitals
Ti2+	2	$t^2_{2g}$
V2+	3	$t^3_{2g}$
Cr3+	3	$t^3_{2g}$
Mn2+	5	$t^3_{2g}e^2_g$
Fe2+	6	$t^4_{2g}e^2_g$
Fe3+	5	$t^3_{2g}e^2_g$
CO2+	7	$t^5_{2g}e^2_g$
Ni2+	8	$t^6_{2g}e^2_g$
Cu2+	9	$t^6_{2g}e^3_g$