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A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
This is a list of chemical elements and their atomic properties, ordered by atomic number (Z). Since valence electrons are not clearly defined for the d-block and f-block elements, there not being a clear point at which further ionisation becomes unprofitable, a purely formal definition as number of electrons in the outermost shell has been used.
A table or chart of nuclides is a two-dimensional graph of isotopes of the elements, in which one axis represents the number of neutrons (symbol N) and the other represents the number of protons (atomic number, symbol Z) in the atomic nucleus. Each point plotted on the graph thus represents a nuclide of a known or hypothetical chemical element.
The periodic table, also known as the periodic table of the elements, is an ordered arrangement of the chemical elements into rows ("periods") and columns ("groups"). It is an icon of chemistry and is widely used in physics and other sciences.
Monoisotopic elements are characterized, except in one case, by odd numbers of protons (odd Z), and even numbers of neutrons. Because of the energy gain from nuclear pairing, the odd number of protons imparts instability to isotopes of an odd Z , which in heavier elements requires a completely paired set of neutrons to offset this tendency into ...
Of the 80 elements with at least one stable isotope, 26 have only one stable isotope. The mean number of stable isotopes for the 80 stable elements is 3.1 stable isotopes per element. The largest number of stable isotopes for a single element is 10 (for tin, element 50).
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For phosphorus (element 15) as an example, the concise form is [Ne] 3s 2 3p 3. Here [Ne] refers to the core electrons which are the same as for the element neon (Ne), the last noble gas before phosphorus in the periodic table.