Editing Period 3 element (section)

{{Short description|Third row of the periodic table}}
{{Morecite|date=March 2024}}
{{Periodic table (micro)| title=Period 3 in the [[periodic table]] | mark=Na,Mg,Al,Si,P,S,Cl,Ar}}
{{Sidebar periodic table|expanded=structure }}
A '''period 3 element''' is one of the [[chemical element]]s in the third row (or [[Periodic table period|period]]) of the [[periodic table|periodic table of the chemical elements]]. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as their atomic number increases: a new row is begun when chemical behavior begins to repeat, meaning that elements with similar behavior fall into the same vertical columns. The third period contains eight elements: sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine and argon. The first two, sodium and magnesium, are members of the [[Block (periodic table)#s-block|s-block]] of the periodic table, while the others are members of the [[Block (periodic table)#p-block|p-block]]. All of the period 3 elements occur in nature and have at least one [[stable isotope]].<ref><span class="plainlinks">[http://scienceaid.co.uk/chemistry/inorganic/period3.html Period 3 Element] {{Webarchive|url=https://web.archive.org/web/20120729193401/http://scienceaid.co.uk/chemistry/inorganic/period3.html |date=2012-07-29 }}</span> from Scienceaid.co.uk</ref>