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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.
1914 — Hackh's periodic table: First spiral to take account of Mosley's atomic numbers, and the first to show successively larger pairs of coils. Also interesting as H stands alone in the centre [77] 1925 — Courtines's a model of the periodic table: A helix with the appearance of a submarine or a castle [78]
Like the periodic table, the list below organizes the elements by the number of protons in their atoms; it can also be organized by other properties, such as atomic weight, density, and electronegativity. For more detailed information about the origins of element names, see List of chemical element name etymologies.
As shown in the following table, there is strong evidence that 19 of the elements are essential to all living things, and another 17 are essential to some taxonomic groups. Of these 17, most have not been extensively studied, and their biological importance may be greater than currently supposed. The remaining elements are not known to be ...
Persons with more fat will have a higher proportion of carbon and a lower proportion of most other elements (the proportion of hydrogen will be about the same). The numbers in the table are averages of different numbers reported by different references. The adult human body averages ~53% water. [7] This varies substantially by age, sex, and ...
41 of the 118 known elements have names associated with, or specifically named for, places around the world or among astronomical objects. 32 of these have names tied to the places on Earth, and the other nine are named after to Solar System objects: helium for the Sun; tellurium for the Earth; selenium for the Moon; mercury (indirectly), uranium, neptunium and plutonium after their respective ...
An extended periodic table theorizes about chemical elements beyond those currently known and proven. The element with the highest atomic number known is oganesson (Z = 118), which completes the seventh period (row) in the periodic table. All elements in the eighth period and beyond thus remain purely hypothetical.
Group 12, by modern IUPAC numbering, [1] is a group of chemical elements in the periodic table. It includes zinc (Zn), cadmium (Cd), mercury (Hg), [ 2 ] [ 3 ] [ 4 ] and copernicium (Cn). [ 5 ] Formerly this group was named IIB (pronounced as "group two B", as the "II" is a Roman numeral ) by CAS and old IUPAC system.