The magnetic properties of an element depend on the number of unpaired electrons it has. Explain why iron, Fe, is highly magnetic but neon, Ne, is not.

The concept of electron configurations is fundamental in understanding the magnetic properties of the elements. An electron configuration represents how electrons are distributed among the orbitals of an atom. For instance, iron (Fe) has the electron configuration [Ar] 3d6 4s2, which means that aside from the core electrons represented by [Ar] (which stands for the configuration of Argon, the noble gas preceding iron), iron has six electrons in the 3d subshell and two electrons in the 4s subshell. The configuration tells us not only the number of electrons but also hints at their arrangement and pairing.

Electron orbitals can hold a certain maximum number of electrons, with s orbitals holding up to two, p orbitals holding up to six, d orbitals up to ten, and so on. Electrons prefer to be paired, that is, two electrons will fill the same orbital with opposite spins. However, when there are more electrons than can be paired, we end up with unpaired electrons, which are incredibly important in determining magnetic properties. Iron, with its four unpaired electrons, has the propensity to be highly magnetic, a characteristic exploited in numerous applications ranging from construction materials to electronic devices.

Understanding how unpaired electrons relate to magnetism is crucial in the discussion of magnetic properties of elements. Each electron carries a magnetic moment due to its spin and orbit around the nucleus. When electrons are unpaired, they do not have another electron with an opposite spin to cancel out their magnetic effect. As a result, the magnetic moments of unpaired electrons add up, enhancing the overall magnetic field of the atom or molecule.

Materials with a significant number of unpaired electrons, like iron, exhibit strong magnetic properties because these unpaired electrons generate magnetic fields that align in the presence of an external magnetic field, resulting in magnetization. Conversely, if all electrons in an element are paired, the opposite spins neutralize each other's magnetic fields, and the material does not exhibit magnetism. This concept underscores why materials with unpaired electrons are often ferromagnetic or paramagnetic, while those with all electrons paired are usually diamagnetic.

The distinct magnetic behaviors of iron (Fe) and neon (Ne) are rooted in their electronic structures. Iron, with its electron configuration of [Ar] 3d6 4s2, has unpaired electrons that do not have a counterpart with an opposite spin. These unpaired electrons' magnetic fields complement each other, giving iron strong magnetic properties that can be observed even at a macroscopic scale - sticking to magnets, forming magnets, or being attracted by magnetic fields. This is the guiding principle behind iron's widespread use in electromagnets and permanent magnets.

Neon, on the other hand, has a full valence shell with the electron configuration 1s2 2s2 2p6. All of its electrons are paired, with their individual magnetic effects canceling each other out. As a result, neon is non-magnetic. This contrast in magnetic properties between iron and neon illustrates the overarching impact of electronic structures on the magnetic character of elements and compounds. It's a vivid demonstration of the link between microscopic electron configurations and macroscopic physical properties.