A nuclide (from lat.: nucleus) is a nuclear species which is characterized by the number of protons and neutrons that every atomic nucleus of this species contains. // Properties [1][2] In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... This article or section does not adequately cite its references or sources. ... Nucleus usually refers to the center of something, but can mean: In science: Atomic nucleus, the collection of protons and neutrons in the center of an atom that carries the bulk of the atoms mass and positive charge Cell nucleus, the membrane-bound subcellular organelle found in eukaryotes, visible...

For a short-hand designation of the nuclide, one writes the mass number (number of nucleons) in the upper left corner and the atomic number (number of protons) in the lower left corner of the chemical symbol, for example: C for the most common isotope of carbon. In earlier years, the mass number was written in the upper right corner. The atomic number may also be omitted, since it is uniquely defined by the element symbol. The mass number (A), also called atomic mass number or nucleon number, is the number of protons plus the number of neutrons in an atomic nucleus. ... In physics a nucleon is a collective name for two baryons: the neutron and the proton. ... It has been suggested that List of elements by atomic number be merged into this article or section. ... // Properties [1][2] In physics, the proton (Greek proton = first) is a subatomic particle with an electric charge of one positive fundamental unit (1. ... A chemical symbol is an abbreviation or short representation of the name of a chemical element. ...

The various nuclides of a particular chemical element with equal proton number (atomic number), but different neutron numbers are called isotopes of this element. Before the term nuclide was internationally accepted (ca. 1950), the term "isotope" was also loosely used to describe a nuclear species, i.e., a nuclide. Nuclides with equal mass number but different atomic number are called isobars (isobar = equal in weight). Isotones are nuclides of equal neutron number but different proton numbers. The periodic table of the chemical elements A chemical element, or element for short, is a type of atom that is defined by its atomic number; that is, by the number of protons in its nucleus. ... Isotopes are any of the several different forms of an element each having different atomic mass (mass number). ... The mass number (A), also called atomic mass number or nucleon number, is the number of protons plus the number of neutrons in an atomic nucleus. ... It has been suggested that List of elements by atomic number be merged into this article or section. ... The word isobar derives from the two ancient Greek words, ισος (isos), meaning equal, and βαρος (baros), meaning weight. In meteorology, an isobar is a line of equal or constant pressure on a graph, plot, or map; an isopleth of pressure. ... Two nuclides are isotones if they have the same number of neutrons. ...

Nuclear isomers are atomic nuclei of a particular nuclide that have equal proton number and equal mass number, differ in energy content and are long-lived (for example the two states of ⁹⁹ Tc shown among the decay schemes). Unstable nuclides are radioactive and are called radionuclides. A nuclear isomer is a metastable or isomeric state of an atom caused by the excitation of a proton or neutron in its nucleus so that it requires a change in spin before it can release its extra energy. ... This article belongs in one or more categories. ... Radioactivity may mean: Look up radioactivity in Wiktionary, the free dictionary. ... A radionuclide is an atom with an unstable nucleus, which is a nucleus characterized of excess energy which is available to be imparted either to a newly-created radiation particle within the nucleus, or else to an atomic electron (see internal conversion) . The radionuclide, in this process, undergoes radioactive decay...

Designation	Characteristics	Example	Remarks
Isotopes	equal proton number	C , C
Isotones	equal neutron number	C , N
Isobars	equal mass number	N , O , F	see beta decay
Mirror nuclei	neutron and proton number exchanged	H , He
Nuclear isomers	different energy states	Tc	long-lived or stable

About 270 stable and about 70 unstable (radioactive) nuclei exist in nature. The natural radioisotopes are those whose half-lives T_1/2 are at least as large as the age of the earth (4,6×10⁹ years) (or they must have long-lived precursors). For example, the isotope ²³⁸U (T_1/2 = 4,5×10⁹ a) of uranium occurs in nature, but also the isotope ²²⁶Ra (T_1/2 = 1602 a) of radium since this is a descendant of ²³⁸U. Many more than 1000 nuclides have been artificially produced. In nuclear physics, beta decay (sometimes called neutron decay) is a type of radioactive decay in which a beta particle (an electron or a positron) is emitted. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Atomic mass 238. ... General Name, Symbol, Number radium, Ra, 88 Chemical series alkaline earth metals Group, Period, Block 2, 7, s Appearance silvery white metallic Atomic mass (226) g·mol−1 Electron configuration [Rn] 7s2 Electrons per shell 2, 8, 18, 32, 18, 8, 2 Physical properties Phase solid Density (near r. ...

The known nuclides are shown in charts of the nuclides (see Weblinks) Also called a Table of Nuclides Description A Chart of Nuclides (capitolization not required) is a way to organize nuclides with a higher degree of classification than is allowed by a periodic table. ...

Weblinks

• Chart of the nuclides
• Details about the nuclides
• Periodic system with details of the nuclides
• Universal Nuclide Chart from Nucleonica