1. (noun) any of five related nonmetallic elements (fluorine or chlorine or bromine or iodine or astatine) that are all monovalent and readily form negative ions

• astatine
• at
• atomic number 85
• atomic number 17
• chlorine
• cl
• atomic number 35
• br
• bromine
• atomic number 53
• i
• iodin
• iodine
• atomic number 9
• f
• fluorine

1. (noun) any of five related nonmetallic elements (fluorine or chlorine or bromine or iodine or astatine) that are all monovalent and readily form negative ions

• group
• grouping