Editing Nonmetal (section)

====Allotropes====
{{multiple image
| perrow            = 3
| total_width       = 350
| align             = right
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| image1            = Diamond-dimd15a.jpg
| alt1              = A clear triangular crystal with a flat face and slightly rough edges
| caption1          = A transparent electrical{{nbsp}}insulator
| image2            = C60-Fulleren-kristallin (cropped).JPG
| alt2              = a haphazard aggregate of brownish crystals
| caption2          = A brownish semiconductor
| image3            = Graphite-233436.jpg
| alt3              = A black multi-layered lozenge-shaped rock
| caption3          = A blackish semimetal
| header            = Three allotropes of carbon
| footer            = From left to right, [[diamond]], [[buckminsterfullerene]], and [[graphite]]
| caption_align     = center
| footer_align      = center
}}
{{Main list|Allotropy#Non-metals|Single-layer materials}}
Over half of the nonmetallic elements exhibit a range of less stable allotropic forms, each with distinct physical properties.<ref>[[#Barton|Barton 2021, p. 200]]</ref> For example, carbon, the most stable form of which is [[graphite]], can manifest as [[diamond]], [[buckminsterfullerene]],<ref>[[#Wiberg|Wiberg 2001, p. 796]]</ref> [[amorphous]]<ref>[[#Shang|Shang et al. 2021]]</ref> and [[Paracrystallinity|paracrystalline]]<ref>[[#Tang|Tang et al. 2021]]</ref> variations. Allotropes also occur for nitrogen, oxygen, phosphorus, sulfur, selenium and iodine.<ref>[[#Steudel|Steudel 2020, ''passim'']]; [[#Carrasco|Carrasco et al. 2023]]; [[#Shanabrook|Shanabrook, Lannin & Hisatsune 1981, pp. 130–133]]</ref>