List of Halogens (Element Groups)

Fluorine and the elements below it on the periodic table are halogens.
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The halogen elements are located in group 17 or VIIA of the periodic table, which is the second-to-last column of the chart. This is a list of elements that belong to the halogen group and a look at the properties that they share in common.

Key Takeaways: Halogens

  • The halogens are the elements in group 17 of the periodic table. This is the next-to-last column of elements on the righthand side of the table.
  • The halogen elements are fluorine, chlorine, bromine, iodine, astatine, and possibly tennessine.
  • The halogens are highly reactive nonmetallic elements. They commonly form ionic bonds with metals and covalent bonds with other nonmetals.
  • The halogens are the only group of elements that include elements in all of the three main states of matter: gases, liquids, and solids.

List of Halogens

Depending on who you ask, there are either 5 or 6 halogens. Fluorine, chlorine, bromine, iodine, and astatine definitely are halogens. Element 117, tennessine, might have some properties in common with the other elements. Even though it is in the same column or group of the periodic table with the other halogens, most scientists believe element 117 behaves more like a metalloid. So little of it has been produced, it's a matter of prediction, not empirical data.

Halogen Properties

These elements share some common properties that distinguish them from other elements on the periodic table.

  • They are highly reactive nonmetals.
  • Atoms of belonging to the halogen group have 7 electrons in their outermost (valence) shell. These atoms need one more electron in order to have a stable octet.
  • The usual oxidation state of a halogen atom is -1.
  • Halogens are highly electronegative, with high electron affinities.
  • The melting and boiling points of the halogens increase as you increase atomic number (as you move down the periodic table).
  • The elements change their state of matter at room temperature and pressure as you increase atomic number. Fluorine and chlorine are gases. Bromine is a liquid element. Iodine is a solid. Scientists predict tennessine is a solid at room temperature.
  • The halogens are colorful, even as gases. Fluorine is the palest element, but even as a gas it has a distinct yellow color.

A Closer Look at the Elements

  • Fluorine is atomic number 9 with element symbol F. At room temperature and pressure, pure fluorine is a pale yellowish gas. But, the element is so reactive it mainly occurs in compounds.
  • Chlorine is atomic number 17 with element symbol Cl. Under ordinary conditions, chlorine is a yellowish-green gas.
  • Bromine is element 35 with symbol Br. It is a liquid at room temperature and pressure.
  • Iodine is element 53 with symbol I. It is a solid under ordinary conditions.
  • Astatine is atomic number 85 with symbol At. It is the rarest naturally-occurring element in the Earth's crust. Astatine is a radioactive element with no stable isotopes.
  • Tennessine is element 117 with symbol Ts. It is a synthetic radioactive element.

Halogen Uses

The lighter halogens occur in living organisms. These are fluorine, chlorine, bromine, and iodine. Of these, chlorine and iodine are essential for human nutrition, although the other elements might also be required in trace amounts.

The halogens are important disinfectants. Chlorine and bromine are used to disinfect water an surfaces. Their high reactivity also makes these elements important components of some types of bleach. Halogens are used in incandescent lamps to make them glow at a higher temperature and with a white color. The halogen elements are important drug components, as they aid drug penetration into tissues.

Sources

  • Bonchev, Danail; Kamenska, Verginia (1981). "Predicting the properties of the 113–120 transactinide elements". The Journal of Physical Chemistry. 85 (9): 1177–86. doi:10.1021/j150609a021
  • Emsley, John (2011). Nature's Building Blocks. ISBN 978-0199605637.
  • Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  • Lide, D. R., ed. (2003). CRC Handbook of Chemistry and Physics (84th ed.). Boca Raton, FL: CRC Press.
  • Morss, Lester R.; Edelstein, Norman M.; Fuger, Jean (2006). Morss, Lester R; Edelstein, Norman M; Fuger, Jean (eds.). The Chemistry of the Actinide and Transactinide Elements. Dordrecht, The Netherlands: Springer Science+Business Media. doi:10.1007/978-94-007-0211-0. ISBN 978-94-007-0210-3.
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Helmenstine, Anne Marie, Ph.D. "List of Halogens (Element Groups)." ThoughtCo, Sep. 7, 2021, thoughtco.com/list-of-halogens-606649. Helmenstine, Anne Marie, Ph.D. (2021, September 7). List of Halogens (Element Groups). Retrieved from https://www.thoughtco.com/list-of-halogens-606649 Helmenstine, Anne Marie, Ph.D. "List of Halogens (Element Groups)." ThoughtCo. https://www.thoughtco.com/list-of-halogens-606649 (accessed September 28, 2021).