Halogen

Halogen is a group of five chemical elements in the periodic table. They are part of Group 17 (VIIA) elements and consist of: fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The term "halogen" means "salt-former" and compounds containing halogens are called "salts".

Properties

All halogens have 7 electrons in their outer shells, giving them the ability to gain an electron to form anions with a -1 charge. They are nonmetals and have similar properties among each other in many sorts of chemical reactions. Halogens are typically reactive and can be harmful or lethal to biological organisms in sufficient quantities.

Fluorine

Fluorine is the most reactive of all elements and no chemical substance is capable of freeing it from its compounds. It is a pale yellow, corrosive gas, which reacts with practically all organic and inorganic substances.

Chlorine

Chlorine is a greenish-yellow gas that combines directly with nearly all elements. It is a vital part of many substances including table salt.

Bromine

Bromine is the only liquid nonmetallic element at room temperature and it evaporates easily. It is a heavy, mobile, reddish-brown liquid.

Iodine

Iodine is a grey, lustrous solid. It volatilizes at ambient temperatures into a pretty blue-violet gas with an irritating odor.

Astatine

Astatine is a radioactive element and it is the heaviest halogen. Its chemical properties are believed to be similar to those of iodine.

Uses

Halogen elements have many uses. For example, they are used in lighting, in the production of fluorocarbons for refrigeration, and in the manufacture of dyes, plastics, and pharmaceuticals. Halogens are also used in the development of photographic film.

Health Effects

Exposure to halogens can have detrimental health effects. For instance, exposure to fluorine can cause significant irritation and injury to the eyes, skin, nose and respiratory tract. Chlorine gas can cause difficulty breathing and chest tightness.

See Also

• Periodic Table
• Chemical Elements
• Chemical Reactions

Halogen Resources
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