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Ions are charged atoms (monatomic ions) or molecules (polyatomic ions). They include cations which have a net positive charge, and anions which have a net negative ...
Ions consisting of only a single atom are termed atomic or monatomic ions, while two or more atoms form molecular ions or polyatomic ions. In the case of physical ionization in a fluid (gas or liquid), "ion pairs" are created by spontaneous molecule collisions, where each generated pair consists of a free electron and a positive ion. [5]
Ionic radius, r ion, is the radius of a monatomic ion in an ionic crystal structure. Although neither atoms nor ions have sharp boundaries, they are treated as if they were hard spheres with radii such that the sum of ionic radii of the cation and anion gives the distance between the ions in a crystal lattice.
Each ion can be either monatomic (termed simple ion), such as sodium (Na +) and chloride (Cl −) in sodium chloride, or polyatomic, such as ammonium (NH + 4) and carbonate (CO 2− 3) ions in ammonium carbonate. Salts containing basic ions hydroxide (OH −) or oxide (O 2−) are classified as bases, such as sodium hydroxide and potassium oxide.
This helps when trying to solve oxidation questions. A charge number also can help when drawing Lewis dot structures. For example, if the structure is an ion, the charge will be included outside of the Lewis dot structure. Since there is a negative charge on the outside of the Lewis dot structure, one electron needs to be added to the structure.
It is usually applied to gases: a monatomic gas is a gas in which atoms are not bound to each other. Examples at standard conditions of temperature and pressure include all the noble gases ( helium , neon , argon , krypton , xenon , and radon ), though all chemical elements will be monatomic in the gas phase at sufficiently high temperature (or ...
A simple example of a polyatomic ion is the hydroxide ion, which consists of one oxygen atom and one hydrogen atom, jointly carrying a net charge of −1; its chemical formula is O H −. In contrast, an ammonium ion consists of one nitrogen atom and four hydrogen atoms, with a charge of +1; its chemical formula is N H + 4.
An iodide ion is the ion I −. [2] Compounds with iodine in formal oxidation state −1 are called iodides. In everyday life, iodide is most commonly encountered as a component of iodized salt, which many governments mandate. Worldwide, iodine deficiency affects two billion people and is the leading preventable cause of intellectual disability ...