The periodic table arranges chemical elements to show their shared properties, discovered by Mendeleev in 1869. It has grown to include 118 elements, with three main versions. The table divides elements into metals and non-metals, with periods and groups identifying similar properties. Other attempts to portray the table have not caught on, but a new spiral version is available for download.
The periodic table of elements is an arrangement of all known chemical elements in such a way as to reveal the periodic repetition of shared properties, discovered in 1869 by Dmitry Ivanovich Mendeleev, a Russian chemist.
Mendeleev was part of a group of international chemists working to establish the atomic weights of the sixty-four elements that were known at that time. The genius of Mendeleev’s arrangement of search results was to not only show the sequence of atomic weights in the horizontal dimension, but also to reveal groupings of elements with similar chemical properties in vertical alignment. It is this arrangement that produces the table of period elements of the name.
As new elements were discovered, the periodic table grew to the point that in 2007 it included 118 elements. The most recent discovery at that time was that of Unonoctiumn – a working name that is Latin for its number – which was artificially produced in 2002 and 2005.
At the beginning of the 21st century, three main versions of the periodic table can be found. The three tabular models are the Chemical Abstract Service (CAS) version, the old version of the International Union of Pure and Applied Chemistry (IUPAC) and the new version of the International Union of Pure and Applied Chemistry (IUPAC).
The old IUPAC version was mainly used in Europe and the CAS system was mainly used in the USA. One major difference is in how they label columns.
Overall, the graphs attempt to work in a similar way. There is a basic division into metals and non-metals. The horizontal lines are called periods and the groups identify elements with similar properties. Some of the notable groups include:
Group 1—alkali metals
Group 2: alkali or alkaline earth metals
Group 3: Elements or transition metals, including the lanthanide series, which were formerly called rare earth metals and the actinide series or radioactive earth metals
Non-metals of group 17: halogens
Group 18: noble or inert gases.
Other attempts to portray the table in other ways, including parallel planes and 3D models, have not caught on. But a new version of Jeff Moran’s spiral periodic table from 2006 is available for download online.
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