What is an anion?

An anion is defined as a negatively charged ion that has gained one or more electrons. In this state, the atom has more electrons than protons, resulting in an overall negative charge. This is a fundamental concept in chemistry, particularly in the study of ionic compounds and reactions, where anions commonly pair with cations, which are positively charged ions, to form stable compounds.

The other options describe different types of atomic or molecular charges. A positively charged atom refers to cations, not anions. A neutral atom has an equal number of electrons and protons, meaning it carries no charge, which sets it apart from an anion. A molecule with no charge is also neutral and does not align with the definition of an anion. Understanding the distinction between these terms is crucial for grasping the larger concepts in chemistry related to ionic bonding and the behavior of elements in various chemical reactions.