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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 radioactive nuclides (sometimes also called isotopes), ordered by half-life from shortest to longest, in seconds, minutes, hours, days and years. Current methods make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds.
For reasons of space, [30] [31] the periodic table is commonly presented with the f-block elements cut out and positioned as a distinct part below the main body. [32] [30] [23] This reduces the number of element columns from 32 to 18. [30] Both forms represent the same periodic table. [6]
This list of nuclides shows observed nuclides that either are stable or, if radioactive, have half-lives longer than one hour. This represents isotopes of the first 105 elements, except for elements 87 ( francium ), 102 ( nobelium ) and 104 ( rutherfordium ).
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.
List of alchemical substances; List of chemical elements; List of minerals – List of minerals with Wikipedia articles; List of named alloys; List of straight-chain alkanes; Polyatomic ion – Ion containing two or more atoms; Exotic molecule – a compound containing one or more exotic atoms
The following 12 pages are in this category, out of 12 total. This list may not reflect recent changes. ... List of chemical elements named after people;
At over 1.9 × 10 19 years, over a billion times longer than the estimated age of the universe, bismuth-209 has the longest known alpha decay half-life of any isotope, and is almost always considered on par with the 80 stable elements. [7] [8] The heaviest elements (those beyond plutonium, element 94) undergo radioactive decay with half-lives ...