A Closer look at the Types of Magnetic Properties in Transition Metals

Transition elements exhibit two forms of magnetic behaviour in the presence of a magnetic field (i) Diamagnetism (ii)paramagnetic   Magnetic fields attract paramagnetic substances while repelling diamagnetic things. Ferromagnetism is a type of paramagnetism in which a substance is strongly drawn to a magnetic field. The presence of unpaired electrons in (n-1)d-orbitals cause paramagnetism, with each such electron having a magnetic moment associated with its spin and orbital motion. The orbital contribution is negligible for the majority of transition elements.

Types of Magnetic Properties in Transition Metals

Paramagnetism (Attracted to Magnetic Field)

The magnetic condition of an atom having one or more unpaired electrons is known as paramagnetism. Due to the magnetic dipole moments of the electrons, a magnetic field attracts the unpaired electrons. Before any orbital to be twice occupied, according to Hund’s Rule, electrons must occupy it singly. This could result in a large number of unpaired electrons in the atom. Unpaired electrons have magnetic properties in both directions because they can spin in either way. Magnetic fields attract paramagnetic atoms because of this ability. O2, or diatomic oxygen, is an excellent example of paramagnetism (described via molecular orbital theory).

Diamagnetism (Repelled by Magnetic Field)

The magnet attracts molecular oxygen (O2) because it is paramagnetic. Molecular nitrogen (N2), on the other hand, has no unpaired electrons and is diamagnetic, meaning it is unaffected by the magnet. The presence of paired electrons, i.e. no unpaired electrons, distinguishes diamagnetic compounds. The electron spins are oriented in different directions according to the Pauli Exclusion Principle, which stipulates that no two electrons may occupy the same quantum state at the same moment. As a result, the magnetic fields of the electrons cancel out, leaving no net magnetic moment and preventing the atom from being attracted to a magnetic field. In fact, as the pyrolytic carbon sheet proved, diamagnetic substances are weakly repelled by a magnetic field.

Ferromagnetism (Permanent Magnet)

The basic mechanism through which certain materials (such as iron) create permanent magnets is known as ferromagnetism. This means the chemical exhibits persistent magnetic properties rather than merely when exposed to an external magnetic field. The electrons of atoms are arranged into domains in a ferromagnetic element, with each domain having the same charge. These domains align up in the presence of a magnetic field, resulting in parallel charges throughout the molecule. The quantity of unpaired electrons in a substance and its atomic size determine whether it is ferromagnetic or not.

In everyday life, ferromagnetism, the persistent magnetism linked with nickel, cobalt, and iron, is a widespread occurrence. Aristotle’s discussion of ferromagnetism in 625 BC, the usage of the compass in 1187, and the modern-day refrigerator are all examples of ferromagnetism understanding and use. In his theory of special relativity, Einstein revealed that electricity and magnetism are intricately intertwined.

Trends of Magnetic Properties in Periodic Table

• The magnetic moment in the 4d and 5d series is determined by the spin and orbital contributions.
• Low spin Fe+3 ion, high spin Fe+2 ion in the first transition series; same with cobalt ions.
• Spinning around the nucleus generates orbital angular momentum (via orbital).
• Because of the constrained rotation and the external environment, this momentum is quenched in most metals.
• There are one or more vacant or half-filled orbitals identical in energy to the orbitals covered by unpaired electrons for orbital angular momentum to contribute. The orbital should be of sufficient energy in this case.

The electrons in this orbital should not have the same spin as rotating electrons. So the electrons can circulate around the nucleus and build orbital momentum by using this neighbouring orbital.

As the unpaired electron number raises from 1 to 5, the magnetic moment of the d horizontal lines raises from 1 to the fifth element in the series. Hence The diamagnetism reduces as the series progresses, but the para magnetism increases.

• In transition metal complexes, magnetism is frequently studied by starting with a precise description of isolated ions and then treating their (exchange) interaction subsequently. We show that this traditional strategy can fail in a variety of situations, particularly in 4d and 5d compounds. We claim that an orbital-selective creation of covalent metal bonds has a significant intersite effect that leads to the exclusion of matching electrons from the magnetic subsystem, and so has a significant impact on the system’s magnetic properties. This effect is particularly noticeable for noninteger electron numbers, as it causes the renowned double exchange, the principal mechanism of ferromagnetism in transition metal compounds, to be suppressed.
• By changing nearest-neighbor distances and interatomic potentials, high pressure has an effect on the band structure and magnetic interactions in materials. While all materials undergo electronic changes as pressure rises, spin polarised, heavily electron correlated materials should see the most severe alterations. Pressure lowers the strength of on-site correlations in such materials (d and f-electron metals and compounds), resulting in greater electron delocalization and, finally, magnetic loss.

Conclusion

Predicting magnetic properties is difficult unless the number of unpaired electrons in the outermost cells can be determined with certainty. The size of the atom and its electronic arrangement are crucial factors. Electronic spin, the quantity of unpaired electrons used to determine how magnetised a molecule is, is used to determine its magnetism. This compound’s most notable feature is that it produces magnets. Because metal complexes have unpaired electrons, they take on a magnetic behaviour.