Isotone

This article is about a concept in nuclear physics. For biochemistry see isotonic

Isotonic

The term isotonic may refer to;*Isotonic for the term associated with muscle contraction*An isotone in nuclear physics*Sports drinks are sometimes designed in an isotonic way to assist athletes rehydrate while balancing electrolytes...

. For the mathematical meaning, see monotone

Monotonic function

In mathematics, a monotonic function is a function that preserves the given order. This concept first arose in calculus, and was later generalized to the more abstract setting of order theory....

.

Two nuclide

Nuclide

A nuclide is an atomic species characterized by the specific constitution of its nucleus, i.e., by its number of protons Z, its number of neutrons N, and its nuclear energy state....

s are isotones if they have the same neutron number

Neutron number

The neutron number, symbol N, is the number of neutrons in a nuclide.Atomic number plus neutron number equals mass number: Z+N=A....

 N, but different proton number Z. For example, boron-12 and carbon-13 nuclei both contain 7 neutron

Neutron

The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...

s, and so are isotones. Similarly, S-36, Cl-37, Ar-38, K-39, and Ca-40 nuclei are all isotones of 20 because they all contain 20 neutrons. Despite its similarity to the Greek

Greek language

Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

 for "same stretching", the term was formed by replacing the "p" in "isotope

Isotope

Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...

" with "n" for "neutron".

See also

• Isotope
  Isotope
  Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
  
  s are nuclides having the same number of protons; e.g. carbon-12 and carbon-13.
• Isobar
  Isobar (nuclide)
  Isobars are atoms of different chemical elements that have the same number of nucleons. Correspondingly, isobars differ in atomic number but not in mass number. An example of a series of isobars would be 40S, 40Cl, 40Ar, 40K, and 40Ca...
  
  s are nuclides having the same mass number
  Mass number
  The mass number , also called atomic mass number or nucleon number, is the total number of protons and neutrons in an atomic nucleus. Because protons and neutrons both are baryons, the mass number A is identical with the baryon number B as of the nucleus as of the whole atom or ion...
  
   (i.e. sum of protons plus neutrons); e.g. carbon-12 and boron-12.
• Nuclear isomer
  Nuclear isomer
  A nuclear isomer is a metastable state of an atomic nucleus caused by the excitation of one or more of its nucleons . "Metastable" refers to the fact that these excited states have half-lives more than 100 to 1000 times the half-lives of the other possible excited nuclear states...
  
  s are different excited states of the same type of nucleus. A transition from one isomer to another is accompanied by emission or absorption of a gamma ray
  Gamma ray
  Gamma radiation, also known as gamma rays or hyphenated as gamma-rays and denoted as γ, is electromagnetic radiation of high frequency . Gamma rays are usually naturally produced on Earth by decay of high energy states in atomic nuclei...
  
  , or the process of internal conversion
  Internal conversion
  Internal conversion is a radioactive decay process where an excited nucleus interacts with an electron in one of the lower atomic orbitals, causing the electron to be emitted from the atom. Thus, in an internal conversion process, a high-energy electron is emitted from the radioactive atom, but...
  
  . (Not to be confused with chemical isomer
  Isomer
  In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...
  
  s.)