Editing Period 7 element (section)

=== S-block ===
{{main|Francium|Radium}}
Francium and radium make up the s-block elements of the 7th period.

'''Francium''' '''(Fr, atomic number 87)''' is a highly [[radioactive]] metal that decays into astatine, [[radium]], or [[radon]]. It is one of the two least [[electronegative]] elements; the other is [[caesium]]<!--, and is the [[Abundance of the chemical elements|second rarest]] naturally occurring element (after [[astatine]])-->. As an [[alkali metal]], it has one [[valence electron]]. Francium was discovered by [[Marguerite Perey]] in [[France]] (from which the element takes its name) in 1939.<ref>{{Cite web |title=Francium {{!}} Radioactive, Alkali Metal, Rare {{!}} Britannica |url=https://www.britannica.com/science/francium |access-date=2023-10-19 |website=www.britannica.com |language=en}}</ref> It was the last element discovered in [[nature]], rather than by synthesis.<ref group="note">Some elements discovered through synthesis, such as [[technetium]], have later been found in nature.</ref> Outside the laboratory, francium is extremely rare, with trace amounts found in [[uranium]] and [[thorium]] ores, where the [[isotope]] francium-223 continually forms and decays. As little as 20–30&nbsp;g (one ounce) exists at any given time throughout [[Earth's crust]]; the other isotopes are entirely synthetic. The largest amount produced in the laboratory was a cluster of more than 300,000 atoms.<ref name=chemnews>{{cite journal|url=http://pubs.acs.org/cen/80th/francium.html|title=Francium|journal=Chemical and Engineering News|year=2003|author=Luis A. Orozco }}</ref>

'''Radium (Ra, atomic number 88)''' is an almost pure-white [[alkaline earth metal]], but it readily [[oxidize]]s, reacting with nitrogen (rather than oxygen) on exposure to air, becoming black in color. All [[isotopes of radium]] are [[radioactive]]; the most stable is [[radium-226]], which has a [[half-life]] of 1601 years and [[Radioactive decay|decays]] into [[radon]]. Due to such instability, radium [[luminescence|luminesces]], glowing a faint blue. Radium, in the form of [[radium chloride]], was [[discovery of the chemical elements|discovered]] by [[Marie Curie|Marie]] and [[Pierre Curie]] in 1898. They extracted the radium compound from [[uraninite]] and published the discovery at the [[French Academy of Sciences]] five days later. Radium was isolated in its [[metal]]lic state by Marie Curie and [[André-Louis Debierne]] through [[electrolysis]] of radium chloride in 1910. Since its discovery, it has given names such as [[radon-222|radium A]] and [[thallium-210|radium C{{sub|2}}]] to several isotopes of other elements that are [[decay product]]s of radium-226. In nature, radium is found in [[uranium]] ores in trace amounts as small as a seventh of a gram per ton of [[uraninite]]. Radium is not necessary for living things, and adverse health effects are likely when it is incorporated into biochemical processes due to its radioactivity and chemical reactivity.