In this article, a deeper look will be taken into halogens, what they are, how they are used in products, and why there is a desire to eliminate their use as a material in products. The word has become so attached to the electrical lighting industry that most people only think in terms of these high-intensity lamps that produce a bright light output and get very hot.īut the word halogen has a broader meaning, and initiatives are actively in place that seek to emphasize that products be manufactured using raw materials that are halogen-free. Reference:, ,, wikipedia.Mention the word “halogen” to someone and chances are what pops into their head is halogen bulbs. Aromatic halogen groups are far less reactive than aliphatic halogen groups, which can exhibit considerable chemical reactivity.

The chemical reactivity of halogen atoms depends on both their point of attachment to the lead and the nature of the halogen. Halogen lamps are a type of incandescent lamp using a tungsten filament in bulbs that have small amounts of a halogen, such as iodine or bromine added. PHCs are used in a vast array of manufactured products and in pest control. Polyhalogenated compounds (PHCs) are highly reactive and also bioaccumulate in humans some of them have toxic and carcinogenic properties. Because of this, some halogenated drugs can accumulate in adipose tissue.

Without iodine, thyroid hormones cannot be produced, which leads to hypothyroidism.ĭrug candidates that have incorporated halogen atoms are usually more lipophilic and less water-soluble than their analogues, and so have improved penetration through lipid membranes and tissues. Iodine is essential for the functioning of the body’s thyroid gland. Compounds of both chlorine and bromine are used as disinfectants for sterilization. However, overconsumption of fluoride can be fatal.Ĭhlorine accounts for about 0.15 percent of human body weight and plays several important roles in the body’s functioning. Probably the most important generalization that can be made about the halogen elements is that they are all oxidizing agents i.e., they raise the oxidation state, or oxidation number, of other elements a property that used to be equated with combination with oxygen but that is now interpreted in terms of transfer of electrons from one atom to another.įluoride can be found in many everyday products, including toothpaste, vitamin supplements, baby formulas, and even public water. As a diatomic molecule, fluorine has the weakest bond due to repulsion between electrons of the small atoms. Halogens are nonmetals in group 17 (or VII) of the periodic table. Halogens show great resemblances to one another in their general chemical behaviour and in the properties of their compounds with other elements. The halogen atoms carry seven valence electrons in their outermost electron shell. Approximately 15,000 metric tons of fluorine gases are made per year.

Fluorine gas is made from hydrofluoric acid produced as a by-product in phosphoric acid manufacture. Four hundred-thousand metric tons of hydrofluoric acids are made each year. Astatine and tennessine do not occur in nature, because they consist of only short-lived radioactive isotopes.Īpproximately six million metric tons of the fluorine mineral fluorite are produced each year. The percentages of the halogens in the igneous rocks of Earth’s crust are 0.06 fluorine, 0.031 chlorine, 0.00016 bromine, and 0.00003 iodine. Elemental halogens are dangerously to potentially lethally toxic. Organobromides are the most important class of flame retardants. The middle halogen, that is chlorine, bromine and iodine, are often used as disinfectants. Most halogens are typically produced from minerals or salts. All halogens have 7 electrons in their outer shells, giving them an oxidation number of -1.Īll of the halogens form acids when bonded to hydrogen. The term “halogen” means “salt-former” and compounds containing halogens are called “salts”. The symbol X is often used generically to refer to any halogen. In the modern IUPAC nomenclature, this group is known as group 17. The artificially created element 117 (tennessine, Ts) may also be a halogen. The halogens are fluorine, chlorine, bromine, iodine, and astatine. Halogens (or halogen elements) are any of a group of five nonmetallic elements with similar properties.

Symbol for halogen