Group 17 Elements: The Halogens

Christyna.H & Nijayah.C

The Elements that are in this Group

  • Flourine (F)
  • Chlorine (Cl)
  • Bromine (Br)
  • Iodine (I)
  • Astattine (At)

Description of each Element


  • Atomic Number- 9
  • Atomic Mass- 19 amu
  • Symbol- (F)
  • Uses- Is in toothpaste and in drinking water to prevent dental cavities.
  • Discovery- Henri Moissan
  • Valence Electrons- 7


  • Atomic Number- 17
  • Atomic Mass- 35 amu
  • Symbol- (Cl)
  • Uses- Is in dyes,textiles, medicines, antiseptics, insecticides and paints.
  • Discovery- Carl Wilhelm Scheele
  • Valence Electrons- 7


  • Atomic Number- 35
  • Atomic Mass- 8- amu
  • Symbol- (Br)
  • Uses- In water treatment in swimming pools and hot tubs.
  • Discovery- Antoine Jermoe
  • Valence Electrons- 7


  • Atomic Number- 53
  • Atomic Mass- 127 amu
  • Symbol- (I)
  • Uses- It is used in Medicine to kill fungus, and bacteria
  • Discovery- Bernard Courtios
  • Valence Electrons- 7


  • Atomic Number- 85
  • Atomic Mass- 21- amu
  • Symbol- (At)
  • Uses- Sometimes used as a a radioactive tracer and in cancer treatment
  • Discovery- Dale Corson
  • Valence Electrons- 7

What they all have in common

Group 17, or the Halogen Group, all have 7 valence electrons and will gain or share an electron when forming compounds with other elements. They are all non-metals except for astatine, which is a metalloid. They are the most reactive non-metals because they only need one more electron to fill the outer shell.

Interesting Facts about Element 17

  • All halogens are electronegative : they gain electrons very quickly, making them the most reactive of all chemical elements.
  • Fluorine are used in non- stick Teflon pans.
  • Halogen means "salt come to be" and it's significant because halogens form salt when reacted near metal.
  • Halogens were names by a Swedish chemist by the name of Jöns Jakob Berzulíus

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