ioonides

Iones are atoms or molecules that have gained or lost one or more electrons, resulting in a net electrical charge. When an atom loses an electron, it becomes a positively charged ion, also known as a cation. Conversely, when an atom gains an electron, it becomes a negatively charged ion, known as an anion. The number of electrons in a neutral atom is equal to the number of protons in its nucleus. This balance is disrupted in ions.

Ions are fundamental to many chemical and biological processes. For example, in solution, ionic compounds like sodium chloride (table salt) dissociate into their constituent ions, sodium cations (Na+) and chloride anions (Cl-). These ions are crucial for electrical conductivity in electrolytes and play vital roles in nerve function and muscle contraction in living organisms. The attraction between oppositely charged ions forms ionic bonds, which hold together many crystalline solids.

The charge of an ion is indicated by a superscript following the element's symbol or chemical formula. A single positive charge is written as +, a double positive charge as 2+, and so on. Similarly, a single negative charge is written as -, and a double negative charge as 2-. The formation of ions is a key concept in understanding chemical reactivity, solubility, and the behavior of matter.