What is an anion?

An anion is defined as a negatively charged ion. This occurs when an atom gains one or more electrons, resulting in a net negative charge due to the excess of negatively charged electrons compared to positively charged protons in its nucleus. Anions play vital roles in various chemical processes, including those involved in biological systems, such as the functions within cells and the transport of nutrients.

In contrast, other options describe different concepts: a positively charged ion is known as a cation, which is not the definition of an anion; a type of acid typically refers to substances that can donate protons or accept electron pairs in reactions, which does not pertain directly to the classification of ions; and forms of radiation are unrelated to the definitions of ions or chemistry in the same context. Understanding the definition and role of anions is key in fields such as biochemistry and nutrition, especially in the context of dairy cattle management, where ionic balance can affect health and productivity.