Algonquin College Health Program Assessment (AC-HPAT) Practice Exam

What is an anion?

1. A positively charged ion

2. A neutrally charged particle

3. A negatively charged ion

4. A type of atomic nucleus

The correct answer is: A negatively charged ion

An anion is defined as a negatively charged ion. This occurs when an atom gains one or more electrons, resulting in an excess of negative charge relative to the number of positively charged protons in the nucleus. The gaining of electrons diminishes the overall electrical balance, leading to a net negative charge. Understanding the formation of anions is essential in various fields, including chemistry and biology, as they play crucial roles in chemical reactions and biological processes. For example, many biological molecules, such as nucleic acids and proteins, can carry anionic charges that influence their structure and function in physiological environments. In contrast, the formation of positive ions (cations) involves the loss of electrons, which is what distinguishes anions from cations. A neutral particle lacks overall charge, while an atomic nucleus refers to the central part of an atom made up of protons and neutrons, not directly related to the concept of ion charge. This background helps clarify why the definition of an anion is specifically linked to a negatively charged ion.