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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 ...
If necessary, a state of ionization or an excited state may be indicated in the right superscript position (e.g., state of ionization Ca 2+). The number of atoms of an element in a molecule or chemical compound is shown in the right subscript position (e.g., N 2 or Fe 2 O 3). If this number is one, it is normally omitted - the number one is ...
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]
The conventional symbol Z comes from the German word Zahl 'number', which, before the modern synthesis of ideas from chemistry and physics, merely denoted an element's numerical place in the periodic table, whose order was then approximately, but not completely, consistent with the order of the elements by atomic weights.
A mnemonic is a memory aid used to improve long-term memory and make the process of consolidation easier. Many chemistry aspects, rules, names of compounds, sequences of elements, their reactivity, etc., can be easily and efficiently memorized with the help of mnemonics.
The first set of commonly used mineral symbols was published in 1983 and covered the common rock-forming minerals using 192 two- or three-lettered symbols. [1] These type of symbols are referred to as Kretz symbols. More extensive lists were subsequently made available in the form of publications [2] [3] or posted on journal webpages. [4]
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Once an element has been named, a one- or two-letter symbol must be ascribed to it so it can be easily referred to in such contexts as the periodic table. The first letter is always capitalized. While the symbol is often a contraction of the element's name, it may sometimes not match the element's English name; for example, "Pb" for lead (from ...