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Instantons are used in nonperturbative calculations of tunneling rates. Instantons have properties similar to particles, specific examples include: Calorons, finite temperature generalization of instantons. Merons, a field configuration which is a non-self-dual solution of the Yang–Mills field equation. The instanton is believed to be ...
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.
Pie charts of typical human body composition by percent of mass, and by percent of atomic composition (atomic percent) Body composition may be analyzed in various ways. This can be done in terms of the chemical elements present, or by molecular structure e.g., water , protein , fats (or lipids ), hydroxyapatite (in bones), carbohydrates (such ...
Cations are positively (+) charged ions while anions are negatively (−) charged. This can be remembered with the help of the following mnemonics. Cats have paws ⇔ Cations are pawsitive. [27] Ca+ion: The letter t in cation looks like a + (plus) sign. [28] An anion is a negative ion. (An egative ion ⇒ Anion). [29]
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 ...
The component ions in a salt can be either inorganic, such as chloride (Cl −), or organic, such as acetate (CH 3 COO −). 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.
The ion can be formed from the ionization of a neutral hydrogen molecule by electron impact. It is commonly formed in molecular clouds in space by the action of cosmic rays . The dihydrogen cation is of great historical, theoretical, and experimental interest.