Halogens are highly reactive, non-metallic elements found in group 17 on the periodic table. Currently, the group halogen includes the elements fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At), all of which are commonly found on Earth except for astatine. Astatine is radioactive and rapidly decays to other, more stable elements resulting in it being one of the least common elements on Earth.
Halogens are among the most reactive of all elements, however, reactivity declines from the top to the bottom of the halogen group. Since all halogens have seven valence electrons, they are all ambitious to gain one more electron for the perfect eight valence electrons, a full outer energy level, which is the most stable arrangement of electrons. A valence electron is an electron in the outermost shell, or energy level, of an atom. Halogens often combine with alkali metals in group 1 on the periodic table, which have just one valence electron, meaning they are ambitious to donate. Reactions that include halogens, especially the halogens closer to the top of the group, can be explosive.
The halogen group is largely varied. It consists of elements that occur in three different states of matter at room temperature, which is roughly 20-22℃ (68-72℉). Fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids. Halogens also vary in color. Fluorine and chlorine are green, bromine is red, and iodine and astatine are nearly black. Like other non-metals, halogens cannot conduct electricity or heat, which means they are insulators and don’t let electricity or heat flow through them easily. Compared to most other elements, halogens have relatively low melting and boiling points, which means they can melt and boil at lower temperatures than most other elements.
Some uses of halogens are fluorine in tooth care, bromine in water purification in swimming pools and hot tubs, and iodine added to alcohol to create an antiseptic. Fluorine is a gaseous halogen that has been shown to prevent tooth decay. That is why it is added to toothpaste in the form of sodium fluoride. Bromine is the only liquid halogen, where when it is in tablet form, it is used to purify water in swimming pools and hot tubs. It reacts with bacteria and other germs and yields them harmless. Iodine is a solid halogen that is added to alcohol to be used as an antiseptic. It reacts with germs on cuts and wounds. Small amounts of iodine are also needed for good health, which is why in the US, iodine is added to table salt to prevent iodine deficiencies.
In conclusion, halogens are highly reactive, non-metal elements in group 17 on the periodic table. They include solids, liquids, and gases at room temperature and vary in color. Halogens are among the most reactive of all elements consisting of seven valence electrons, causing them to be ambitious to gain one more electron to create the full outer energy level, which is the most stable arrangement of electrons. Halogens have a variety of important uses, such as preventing tooth decay and killing germs.
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By: Zubin Sidhu
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References:
“4.11 Halogens.” CK-12, flexbooks.ck12.org/cbook/ck-12-middle-school-physical-science-flexbook-2.0/section/4.11/primary/lesson/halogens-ms-ps. Accessed 13 Mar. 2021.
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