What is a cation?

A cation is defined as an atom that has lost one or more electrons, resulting in a net positive charge. When an atom loses electrons, it has more protons than electrons, leading to that positive charge. This process typically occurs with metals, which tend to have a lower electronegativity and readily lose electrons to achieve a stable electronic configuration.

The other choices describe different concepts in atomic structure. An atom that gains electrons becomes an anion, which is negatively charged. An atom with an equal number of protons and electrons is electrically neutral, which aligns with the definition of a neutral atom rather than a cation. Lastly, an atom that has a neutral charge is simply at equilibrium regarding its charge balance and does not fit the definition of a cation either.