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The chemical elements are what the periodic table classifies and organizes. Hydrogen is the element with atomic number 1; helium, atomic number 2; lithium, atomic number 3; and so on. Each of these names can be further abbreviated by a one- or two-letter chemical symbol; those for hydrogen, helium, and lithium are respectively H, He, and Li. [6]
Hydrogen is set to an abundance of 12 on this scale. The Sun's photosphere consists mostly of hydrogen and helium; the helium abundance varies between about 10.3 and 10.5 depending on the phase of the solar cycle; [13] carbon is 8.47, neon is 8.29, oxygen is 7.69 [14] and iron is estimated at 7.62. [15]
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).
Lithium is the first alkali metal in the periodic table, [note 1] and the first metal of any kind in the periodic table. [note 2] At standard temperature and pressure, lithium is a soft, silver-white, highly reactive metal. With a density of 0.564 g⋅cm −3, lithium is the lightest metal and the least dense solid element. [6]
Hydrogen: Helium: Lithium: ... Although group 12 lies in the d-block of the modern 18-column periodic table, the d ... and is commonly used in electroplating. [20] ...
Most helium was formed during the Big Bang, but new helium is created through nuclear fusion of hydrogen in stars. [5] On Earth, helium is relatively rare, only occurring as a byproduct of the natural decay of some radioactive elements. [6] Such 'radiogenic' helium is trapped within natural gas in concentrations of up to seven percent by volume ...
In the periodic table of the elements, each column is a group. In chemistry, a group (also known as a family) [1] is a column of elements in the periodic table of the chemical elements. There are 18 numbered groups in the periodic table; the 14 f-block columns, between groups 2 and 3, are not numbered.
Data table: electronegativities of the elements Number Symbol Name electronegativity WEL CRC LNG; 1: H: hydrogen: 2.20: same 2: He: helium: no data: same 3: Li ...