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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 ...
The term derives from lanthanum, first discovered in 1838, at that time a so-called new rare-earth element "lying hidden" or "escaping notice" in a cerium mineral, [12] and it is an irony that lanthanum was later identified as the first in an entire series of chemically similar elements and gave its name to the whole series.
Lanthanum is a chemical element with the symbol La and the atomic number 57. It is a soft , ductile , silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table , of which lanthanum is the first and the prototype.
By then the number of known rare-earth elements had reached six: yttrium, cerium, lanthanum, didymium, erbium, and terbium. Nils Johan Berlin and Marc Delafontaine tried also to separate the crude yttria and found the same substances that Mosander obtained, but Berlin named (1860) the substance giving pink salts erbium , and Delafontaine named ...
Periodic tables usually at least show the elements' symbols; many also provide supplementary information about the elements, either via colour-coding or as data in the cells. The above table shows the names and atomic numbers of the elements, and also their blocks, natural occurrences and standard atomic weights. For the short-lived elements ...
The Americas, as the element was first synthesised on the continent, by analogy with europium: 96: Cm: Curium: Pierre Curie and Marie Curie, French physicists and chemists 97: Bk: Berkelium: Berkeley, California, where the element was first synthesised, by analogy with terbium: 98: Cf: Californium: California, where the element was first ...
An 1888 reproduction of a Venetian list of medieval Greek alchemical symbols from about the year 1100 but circulating since about 300 and attributed to Zosimos of Panopolis. The list starts with 🜚 for gold and has early conventions that would later change: here ☿ is tin and ♃ electrum; ☾ is silver but ☽ is mercury.
A period 6 element is one of the chemical elements in the sixth row (or period) of the periodic table of the chemical elements, including the lanthanides.The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements ...