What are ions?

Ions are defined as atoms or molecules that have gained or lost one or more electrons, resulting in a net electric charge. This means that they can either be positive or negative charged entities. When an atom loses electrons, it becomes positively charged and is referred to as a cation. Conversely, when it gains electrons, it becomes negatively charged, known as an anion. Thus, the correct answer highlights that ions are electrically charged atoms or molecules, encompassing both positively and negatively charged forms.

The other options don't accurately depict the nature of ions. For example, positively charged particles only would misrepresent the existence of anions. Neutral particles fail to address the charge aspect entirely, as they do not represent ions at all. Negatively charged molecules, while they might indicate anionic ion presence, do not encompass the full definition of ions since they exclude cations.