A radical is indicated by a dot on the right side (e.g., Cl.If this number is one, it is normally omitted - the number one is implicitly understood if unspecified. 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 2O 3).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 atomic number is redundant to the chemical element, but is sometimes used to emphasize the change of numbers of nucleons in a nuclear reaction. The proton number ( atomic number) may be indicated in the left subscript position (e.g., 64Gd).These details can be omitted if not relevant in a certain context. Alternately, the number here can represent a specific spin state (e.g., 1O 2). Various letters, such as "m" and "f" may also be used here to indicate a nuclear isomer (e.g., 99mTc). This number defines the specific isotope. The nucleon number ( mass number) is shown in the left superscript position (e.g., 14N).A few isotopes have their own specific symbols rather than just an isotopic detail added to their element symbol.Īttached subscripts or superscripts specifying a nuclide or molecule have the following meanings and positions: 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. There are also some historical symbols that are no longer officially used. For example, "Uno" was the temporary symbol for hassium (element 108) which had the temporary name of unniloctium, based on the digits of its atomic number.
Some symbols come from other sources, like W for tungsten ( Wolfram in German) which was not known in Roman times.Ī three-letter temporary symbol may be assigned to a newly synthesized (or not yet synthesized) element. 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. For some elements, this is because the material was known in ancient times, while for others, the name is a more recent invention. Earlier symbols for chemical elements stem from classical Latin and Greek vocabulary.
0 kommentar(er)
