Nẹ́ọ̀nù ni ẹ́límẹ̀ntì kẹ́míkà kan tó ní àmí-ìdámọ̀ Ne àti nọ́mbà átọ̀mù 10. Ó wà nínú ẹgbẹ́ 18 (àwọn ẹ̀fúùfù abíire) lórí tábìlì ìdásìkò àwọn ẹ́límẹ̀ntì. Lábẹ́ àwọn ìṣẹ̀lẹ̀ déédé nẹ́ọ̀nù jẹ́ ẹ́fúùfù oníátọ̀mùkan aláìláwọ̀, aláìlóòórùn, ó jẹ́ ìdá méjì nínú mẹ́ta ìjẹ́kíki afẹ́fẹ́. Ó jé wíwárí (papọ̀ mọ́ kríptónì àti ksẹ́nọ́nù) ní 1898 gẹ́gẹ́bí ìkan nínú àwọn ẹ́límẹ̀ntì àìgbéra tósọ̀wọ́n tó ṣẹ́kù nínú afẹ́fẹ́ gbígbẹ, lẹ́yìn tí nítrójìn, ọ́ksíjìn, árgọ̀nù àti dìọ́ksídì kárbọ̀nù ti jẹ́ yíyọ kúrò. Nẹ́ọ̀nù ni ó jẹ́ èkejì nínú àwọn ẹ̀fúùfù àṣọ̀wọ́n mẹ́tẹ̀ẹ̀ta tó jẹ́ wíwárí, ó sí jẹ́ dídámọ̀ kíákíá bíi ẹ́límẹ̀ntì tuntun nítorí ìgbàjá-àwọ̀ ìtúsíta pupa rẹ̀. Orúkọ rẹ̀ wá láti ọ̀rọ̀ èdè Grííkì tó túmọ̀sí "ohun tuntun." Nẹ́ọ̀nù jẹ́ aláìgbéra bíi kẹ́míkà, kò sì lè dá àdàpọ̀ kẹ́míkà aláìní-àgbérù.
During cosmic nucleogenesis of the elements, large amounts of neon are built up from the alpha-capture fusion process in stars. Although neon is a very common element in the universe and solar system (it is fifth in cosmic abundance after hydrogen, helium, oxygen and carbon), it is very rare on Earth. It composes about 18.2 ppm of air by volume (this is about the same as the molecular or mole fraction), and a smaller fraction in the crust. The reason for neon's relative scarcity on Earth and the inner (terrestrial) planets, is that neon forms no compounds to fix it to solids, and is highly volatile, therefore escaping from the planetesimals under the warmth of the newly-ignited Sun in the early Solar System. Even the atmosphere of Jupiter is somewhat depleted of neon, presumably for this reason.
↑Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry88 (3): 265–91. doi:10.1515/pac-2015-0305.
↑"Section 4, Properties of the Elements and Inorganic Compounds; Melting, boiling, triple, and critical temperatures of the elements". CRC Handbook of Chemistry and Physics (85th edition ed.). Boca Raton, Florida: CRC Press. 2005.