What characterizes a paramagnetic atom?

A paramagnetic atom is characterized by having at least one unpaired electron in its atomic or molecular structure. This unpaired electron allows the atom to be attracted to a magnetic field, making the substance exhibit magnetic properties.

In contrast, if all electrons were paired up, the atom would be diamagnetic and would not show any attraction to a magnetic field. The presence of unpaired electrons is essential in distinguishing paramagnetism from diamagnetism.

The idea of a complete outer shell relates more to an atom's overall stability and chemical reactivity rather than its magnetic properties. Atoms with a complete outer shell (such as noble gases) do not have unpaired electrons and are generally not paramagnetic. Additionally, the ability to form ions is a characteristic related to an atom's valence electrons and does not directly correlate with being paramagnetic or diamagnetic; hence, it does not characterize a paramagnetic atom.