Editing Nonmetal (section)

=== Unclassified nonmetals ===
{{anchor|Unclassified nonmetal|right}}

[[File:Selenium black (cropped).jpg|thumb|right|[[Selenium]] conducts electricity around 1,000 times better [[photoconductor|when light falls on it]], a property used in [[Photodetector|light-sensing applications]].<ref>[[#Emsley2011|Emsley 2011, p. 478]]</ref>|alt=A small glass jar filled with small dull grey concave buttons. The pieces of selenium look like tiny mushrooms without their stems.]]

{{Anchor|Hlike a metal}}Hydrogen behaves in some respects like a metallic element and in others like a nonmetal.<ref>[[#Seese|Seese & Daub 1985, p. 65]]</ref> Like a metallic element it can, for example, form a [[solvation|solvated cation]] in [[aqueous solution]];<ref>[[#MacKay|MacKay, MacKay & Henderson 2002, pp. 209, 211]]</ref> it can substitute for [[alkali metal]]s in compounds such as the chlorides ([[sodium chloride|NaCl]] cf. [[hydrochloric acid|HCl]]) and nitrates ([[potassium nitrate|KNO<sub>3</sub>]] cf. [[nitric acid|HNO<sub>3</sub>]]), and in certain alkali metal [[organometallic chemistry|complexes]]<ref>[[#Cousins|Cousins, Davidson & García-Vivó 2013, pp. 11809–11811]]</ref><ref name="Cao4">[[#Cao|Cao et al. 2021, p. 4]]</ref> as a nonmetal.<ref>[[#Liptrot|Liptrot 1983, p. 161]]; [[#MD|Malone & Dolter 2008, p. 255]]</ref> It attains this configuration by forming a covalent or ionic bond<ref name="Wiberg255–257">[[#Wiberg|Wiberg 2001, pp. 255–257]]</ref> or by bonding as an ion to a lone pair of electrons.<ref>[[#Scott1962|Scott & Kanda 1962, p. 153]]</ref>

Some or all of these nonmetals share several properties. Being generally less reactive than the halogens,<ref>[[#Taylor|Taylor 1960, p. 316]]</ref> most of them can occur naturally in the environment.<ref name="Emsley"/> Collectively, their physical and chemical characteristics can be described as "moderately non-metallic".<ref name="Cao20">[[Nonmetal#Cao|Cao et al. 2021, p. 20]]</ref> When combined with metals, the unclassified nonmetals can form [[interstitial compound|interstitial]] or [[refractory]] compounds.<ref>[[#Mess|Messler 2011, p. 10]]</ref> They also exhibit a tendency to [[catenation|bond to themselves]], particularly in solid compounds.<ref>[[#King1994|King 1994, p. 1344]]; [[#Powell|Powell & Tims 1974, pp. 189–191]]; [[#Cao|Cao et al. 2021, pp. 20–21]]</ref> Additionally, [[Diagonal relationship|diagonal periodic table relationships]] among these nonmetals mirror similar relationships among the metalloids.<ref>[[#Vernon2020|Vernon 2020, pp. 221–223]]; [[#RaynerW|Rayner-Canham 2020, p. 216]]</ref>