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.
- Fluorine
- Chlorine
- Bromine
- Iodine
- Astatine
- Tennessine (might behave as a halogen, at least in some respects)
Read MoreHalogen Elements and PropertiesBy Anne Marie Helmenstine, Ph.D.
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(84thed.). 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.
FAQs
In the periodic table the halogens make up Group 17 (according to the numbering system adopted by the International Union of Pure and Applied Chemistry), the group immediately preceding the noble gases. The halogen atoms carry seven valence electrons in their outermost electron shell.
What are the 5 halogens? ›
Halogens are generally considered to be any of the group of five chemical elements of the periodic table consisting of fluorine (F), chlorine (CI), bromine (Br), iodine (I) and astatine (At). This group of elements had traditionally been known as Group 7A and is currently referred to as Group 17.
How many valence electrons do halogens have ____ and they are _____? ›
Halogens are among the most reactive of all elements. They have seven valence electrons, so they are very “eager” to gain one electron to have a full outer energy level.
How many halogens do we have? ›
The halogens (/ˈhælədʒən, ˈheɪ-, -loʊ-, -ˌdʒɛn/) are a group in the periodic table consisting of six chemically related elements: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and the radioactive elements astatine (At) and tennessine (Ts), though some authors would exclude tennessine as its chemistry is ...
Is halogen group 7 or 17? ›
The halogens are located on the left of the noble gases on the periodic table. These five toxic, non-metallic elements make up Group 17 of the periodic table and consist of: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).
Why are group 7 called halogens? ›
The word halogen means 'salt forming' compounds. Since all halogens have 7 electrons in their valence shell, they react rapidly with metals to form salts. Thus, the seventh group of elements is known as Halogens.
What are the 7 elements of the halogens? ›
Key Takeaways: Halogens
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.
Why are 17 called halogens? ›
The group 17 elements include fluorine(F), chlorine(Cl), bromine(Br), iodine(I) and astatine(At) from the top to the bottom. They are called “halogens” because they give salts when they react with metals.
Are there 6 or 7 noble gases? ›
noble gas, any of the seven chemical elements that make up Group 18 (VIIIa) of the periodic table. The elements are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og).
What do group 7 halogens do to become stable and have a full outside shell? ›
For stability, the atom needs to have a full outer shell. Group 7 elements need to gain 1 electron to have a full shell. As we descend the group: there are more shells between the nucleus and the outer electron.
Actinides are a group of 15 elements with atomic numbers ranging from 89 to 103. Actinium , the initial component in the series, inspired their names.
What do halogens react with? ›
Halogens react readily with all sorts of metals, including groups 1, 2, 3 and transition metals. They also react with hydrogen. When reacting with metals, halogens form salts with a giant ionic structure, and when reacting with hydrogen, they form hydrogen halides.
Why are halogens toxic? ›
- Halogens are highly reactive and as such can be harmful or lethal to biological organisms in sufficient quantities. This reactivity is due to the high electronegativity of the atoms due to their high effective nuclear charge.
What is unique about halogens? ›
Halogens are unique because they have seven valence electrons which makes them very reactive. Valence electrons are contained in the outer shell and are the electrons that are involved in chemical reactions. The outer shell needs to have eight electrons to be non-reactive and stable.
What are the most common halogens? ›
Of the halogens, fluorine has the highest crustal abundance (544 mg/kg) while iodine has the lowest (0.25 mg/kg), however, chlorine is by far the most abundant halogen in the cosmos.
How many electrons do halogens have _____ in their outermost shell? ›
Answer and Explanation:
Halogens have seven electrons in their outer shells. Electrons are the negatively charged particles that orbit the nucleus of an atom in various energy levels, or shells.
What does group 7 elements have 7 electrons in their outer shell mean? ›
all have seven electrons. in their outer shell. This means that the halogens. The name 'halogen' means 'salt-producing' because halogens produce a range of salts when they react with metals.
What element has 7 electrons in its outer shell? ›
Fluorine (F) and chlorine (Cl), as group 17 elements, have seven electrons in their outermost shells. They tend to achieve a stable octet by taking an electron from other atoms, becoming negatively charged ions: F− and Cl−.
How many electrons do elements in Group VII 17 have in their valence shell? ›
Group 17 has 7 valence electrons.
