atomic number 9

Definitions of atomic number 9
  1. noun
    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
    synonyms: F, fluorine
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    type of:
    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
    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
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