Editing Periodic table (section)

=== Presentation forms<span class="anchor" id="The long- or 32-column table"></span> ===
<div style="border:1px solid grey; float:right; text-align:center; padding:0.2em; margin:0; font-size:90%;">
{{Periodic table (32 columns, micro)}}
32 columns
{{Periodic table (18 columns, micro)}}
18 columns
</div>
For reasons of space,<ref name=Petrucci331/><ref>{{cite journal |last1=Pfeiffer |first1=Paul |date=1920 |title=Die Befruchtung der Chemie durch die Röntgenstrahlenphysik |url=https://link.springer.com/article/10.1007/BF02448807 |journal=Naturwissenschaften |language=de |volume=8 |issue=50 |pages=984–991 |bibcode=1920NW......8..984P |doi=10.1007/BF02448807 |s2cid=7071495}}</ref> the periodic table is commonly presented with the f-block elements cut out and positioned as a distinct part below the main body.<ref name="cartoon" /><ref name="Petrucci331" /><ref name="Fluck" /> This reduces the number of element columns from 32 to 18.<ref name=Petrucci331/>

Both forms represent the same periodic table.<ref name="IUPAC-redbook" /> The form with the f-block included in the main body is sometimes called the 32-column<ref name="IUPAC-redbook" /> or long form;<ref name="Thyssen" /> the form with the f-block cut out the 18-column<ref name="IUPAC-redbook" /> or medium-long form.<ref name="Thyssen" /> The 32-column form has the advantage of showing all elements in their correct sequence, but it has the disadvantage of requiring more space.<ref>Scerri, p. 375</ref> The form chosen is an editorial choice, and does not imply any change of scientific claim or statement. For example, when discussing [[Group 3 element#Composition|the composition of group 3]], the options can be shown equally (unprejudiced) in both forms.<ref name="2015IUPAC">{{cite web|url=https://iupac.org/projects/project-details/?project_nr=2015-039-2-200|title=The constitution of group 3 of the periodic table|publisher=IUPAC|access-date=30 July 2016|date=2015|url-status=live|archive-url=https://web.archive.org/web/20160705053631/https://iupac.org/projects/project-details/?project_nr=2015-039-2-200|archive-date=5 July 2016}}</ref>

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 weight]]s. For the short-lived elements without standard atomic weights, the mass number of the most stable known isotope is used instead. Other tables may include properties such as state of matter, melting and boiling points, densities, as well as provide different classifications of the elements.{{efn|See for example [https://www.sigmaaldrich.com/SG/en/product/aldrich/z543209 the periodic table poster sold by Sigma-Aldrich.]}}