## Chemistry and Chemical Reactivity (9th Edition)

a) Cr (group 6, period 4): $[Ar]\ 3d^5\ 4s^1$ Removing three electrons: $Cr^{3+}$: $[Ar]\ 3d^3$ b) Both are paramagnetic since they have unpaired electrons, but $Cr^{2+}$ has 4 unpaired, thus being more paramagnetic. c) Since radius increases from top to bottom on the periodic table, the radius of $Al^{3+}$ should be smaller than 64 pm since Al is in the third period.