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List of chemical elements. 118 chemical elements have been identified and named officially by IUPAC. 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]
This is a list of chemical elements and their atomic properties, ordered by Atomic number. 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.
This is called the atomic number, often symbolised Z (for "Zahl" — German for "number"). Each distinct atomic number therefore corresponds to a class of atom: these classes are called the chemical elements. The chemical elements are what the periodic table classifies and organises. Hydrogen is the element with atomic number 1; helium, atomic ...
The atomic number or nuclear charge number (symbol Z) of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei composed of protons and neutrons, this is equal to the proton number ( np) or the number of protons found in the nucleus of every atom of that element. The atomic number can be used to uniquely identify ...
A chemical element is a chemical substance that cannot be broken down into other substances by chemical reactions. The basic particle that constitutes a chemical element is the atom. Elements are identified by the number of protons in their nucleus, [1] known as the element's atomic number. [2] For example, oxygen has an atomic number of 8 ...
An element's atomic number, which is defined as the element's position on the periodic table, corresponds to the number of protons it has in its nucleus. The atomic weight of each element is higher than its proton number, so Rutherford hypothesized that the surplus weight was carried by unknown particles with no electric charge and a mass equal ...
Predictions ranged from atomic number 90 (thorium) to 99, many of which proposed a beginning beyond the known elements (at or beyond atomic number 93). The elements from actinium to uranium were instead believed to form part of a fourth series of transition metals because of their high oxidation states; accordingly, they were placed in groups 3 ...
The discoveries of the 118 chemical elements known to exist as of 2024 are presented here in chronological order. The elements are listed generally in the order in which each was first defined as the pure element, as the exact date of discovery of most elements cannot be accurately determined. There are plans to synthesize more elements, and it ...