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In chemistry, a symbol is an abbreviation for a chemical element. Symbols for chemical elements normally consist of one or two letters from the Latin alphabet and are written with the first letter capitalised. Earlier symbols for chemical elements stem from classical Latin and Greek vocabulary. For some elements, this is because the material was known in ancient times, while for others, the name is a more recent invention. For example, Pb is the symbol for lead (plumbum in Latin); Hg is the symbol for mercury (hydrargyrum in Greek); and He is the symbol for helium (a new Latin name) because helium was not known in ancient Roman times. Some symbols come from other sources, like W for tungsten (Wolfram in German) which was not known in Roman times. A 3-letter temporary symbol may be assigned to a newly synthesized (or not-yet synthesized) element. For example, "Uno" was the temporary symbol for hassium (element 108) which had the temporary name of unniloctium, based on its atomic number being 8 greater than 100. There are also some historical symbols that are no longer officially used. In addition to the letters for the element itself, additional details may be added to the symbol as superscripts or subscripts a particular isotope, ionization, or oxidation state, or other atomic detail. A few isotopes have their own specific symbols rather than just an isotopic detail added to their element symbol. Attached subscripts or superscripts specifying a nuclide or molecule have the following meanings and positions: In Chinese, each chemical element has a dedicated character, usually created for the purpose (see Chemical elements in East Asian languages). However, Latin symbols are also used, especially in formulas. Many functional groups also have their own chemical symbol, e.g. Ph for the phenyl group, and Me for the methyl group. A list of current, dated, as well as proposed and historical signs and symbols is included here with its signification. Also given is each element's atomic number, atomic weight, or the atomic mass of the most stable isotope, group and period numbers on the periodic table, and etymology of the symbol. Hazard pictographs are another type of symbols used in chemistry.
References
- Z is the standard symbol for atomic number
- "Periodic Table – Royal Society of Chemistry" (in en). https://www.rsc.org/periodic-table.
- "Online Etymology Dictionary" (in en). https://www.etymonline.com/.
- Wieser, Michael E.; Holden, Norman (2013). "Atomic weights of the elements 2011 (IUPAC Technical Report)". Pure Appl. Chem. 85 (5): 1047–1078. doi:10.1351/PAC-REP-13-03-02. (for standard atomic weights of elements) https://dx.doi.org/10.1351%2FPAC-REP-13-03-02
- Sonzogni, Alejandro. "Interactive Chart of Nuclides". National Nuclear Data Center: Brookhaven National Laboratory. https://www.nndc.bnl.gov/nudat2/. Retrieved 2008-06-06. (for atomic weights of elements with atomic numbers 103–118)
- The isotopic composition of this element varies in some geological specimens, and the variation may exceed the uncertainty stated in the table.
- The isotopic composition of the element can vary in commercial materials, which can cause the atomic weight to deviate significantly from the given value.
- The isotopic composition varies in terrestrial material such that a more precise atomic weight can not be given.
- The value listed is the conventional atomic-weight value suitable for trade and commerce. The actual value may differ depending on the isotopic composition of the sample. Since 2009, IUPAC provides the standard atomic-weight values for these elements using the interval notation. The corresponding standard atomic weights are: Hydrogen: [1.00784, 1.00811] Lithium: [6.938, 6.997] Boron: [10.806, 10.821] Carbon: [12.0096, 12.0116] Nitrogen: [14.00643, 14.00728] Oxygen: [15.99903, 15.99977] Magnesium: [24.304, 24.307] Silicon: [28.084, 28.086] Sulfur: [32.059, 32.076] Chlorine: [35.446, 35.457] Argon: [39.792, 39.963] Bromine: [79.901, 79.907] Thallium: [204.382, 204.385]
- The atomic weight of commercial lithium can vary between 6.939 and 6.996—analysis of the specific material is necessary to find a more accurate value.
- The element does not have any stable nuclides, and a value in brackets, e.g. [209], indicates the mass number of the longest-lived isotope of the element. However, four such elements, bismuth, thorium, protactinium, and uranium, have characteristic terrestrial isotopic compositions, and thus their standard atomic weights are given.
- Name changed due to a standardization of, modernization of, or update to older formerly-used symbol.
- Holden, N. E. (12 March 2004). "History of the Origin of the Chemical Elements and Their Discoverers". National Nuclear Data Center. https://www.nndc.bnl.gov/content/elements.html.
- Name designated by discredited/disputed claimant.
- Leal, João P. (2013). "The Forgotten Names of Chemical Elements". Foundations of Science 19 (2): 175–183. doi:10.1007/s10699-013-9326-y. https://dx.doi.org/10.1007%2Fs10699-013-9326-y
- http://www.encyclopediaofalabama.org/article/h-1672
- Name proposed prior to discovery/creation of element or prior to official re-naming of a placeholder name.
- Praseodymium on was.chemistryexplained.com. http://was.chemistryexplained.com/elements/P-T/Praseodymium.html
- Temporary placeholder name.
- IUPAC. "Isotopically Modified Compounds". IUPAC. http://www.chem.qmul.ac.uk/iupac/sectionH/. Retrieved 31 March 2015.
- Morgan, G. T., ed (1905). "Annual Reports on the Progress of Chemistry for 1904". Journal of the Chemical Society (Gurney & Jackson) 1: 268. "In view of the extraordinarily complex nature of the later changes occurring in Radium, Rutherford has proposed a new and convenient system of nomenclature. The first product of the change of the radium emanation is named radium A, the next radium B, and so on.".
- Jurczyk, M.; Rajewski, W.; Majchrzycki, W.; Wójcik, G. (1999-08-30). "Mechanically alloyed MmNi5-type materials for metal hydride electrodes". Journal of Alloys and Compounds 290 (1–2): 262–266. doi:10.1016/S0925-8388(99)00202-9. https://dx.doi.org/10.1016%2FS0925-8388%2899%2900202-9
