Question: (a) What behaviour distinguishes paramagnetic and diamagnetic substances?

(b) Why are paramagnetic ions common among transition elements but not main-group elements?

(c) Why are coloured solutions of metal ions common among transition elements but not main-group elements?

A magnetic field repels diamagnetic materials, and they lose their magnetic qualities when the external field is removed. A magnetic field attracts paramagnetic materials, but they lose their magnetic properties when the external field is removed.

a)

Because the outer level of most main-group metal ions is filled with paired electrons, they are diamagnetic and colourless (the ion cannot absorb visible light because it lacks an accessible orbital to receive excited electrons). Transition elements, unlike main-group metal ions, are generally paramagnetic because they have a d sublevel available for accepting excited electrons and may absorb visible light, giving them colour.

b)

Most transition elements are paramagnetic due to unpaired electrons in the d sublevel that can absorb visible wavelengths and travel to higher orbitals, whereas main-group elements are diamagnetic due to filled outer levels with only much higher orbitals available for accepting electrons.

c)

To transfer electrons from the d sublevel to higher energy orbitals, most transition metals require low energy, which is visible. To transport electrons from filled outer levels to higher energy orbitals, main-group elements require much more energy, which is not apparent.