atomic number 9


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Related to atomic number 9: atomic number 16, atomic number 100
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Noun1.atomic number 9 - a nonmetallic univalent element belonging to the halogensatomic number 9 - a nonmetallic univalent element belonging to the halogens; usually a yellow irritating toxic flammable gas; a powerful oxidizing agent; recovered from fluorite or cryolite or fluorapatite
chemical element, element - any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter
cryolite, Greenland spar - a white mineral consisting of fluorides of aluminum and sodium; a source of fluorine
fluorapatite - a form of apatite in which fluorine predominates over chlorine
fluor, fluorite, fluorspar - a soft mineral (calcium fluoride) that is fluorescent in ultraviolet light; chief source of fluorine
gas - a fluid in the gaseous state having neither independent shape nor volume and being able to expand indefinitely
halogen - any of five related nonmetallic elements (fluorine or chlorine or bromine or iodine or astatine) that are all monovalent and readily form negative ions