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| Atoms and Molecules - Periodic Table |
The halogens are located in Group VII, now known as Group 17, of the periodic table. Included in the halogen family are the elements fluorine, chlorine, bromine, iodine, and astatine (F, Cl, Br, I, and At, respectively). Halogens are fairly reactive due to their seven valence electrons. They are very close to the desired octet, and easily pick up one electron. Due to their reactivity, halogens are only found in nature when they are in a molecular compound. Fluorine and chlorine are gases at room temperature. Bromine is a liquid at room temperature, and iodine and astatine are solids at room temperature.
History
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Discoverer/Developer
The halogens were named by a Swedish chemist by the name of Jöns Jakob Berzelius. Halogen means "salt come to be" and is significant because halogens form salts when reacted with metals.
Real World Application
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Fluorine
Fluorine is used in non-stick Teflon pans. Fluorine is also used to etch glass and is an ingredient in toothpaste. CFCs, or chlorofluorocarbons, are a main component in refrigeration and cooling units. Fluorine has been added in very small quantities to public water supplies to reduce tooth decay.
Chlorine
The use of chlorine is quite common. You may recognize the smell of chlorine in public swimming pools or bleach. This is because chlorine makes an excellent disinfectant. One of the most common applications of chlorine is in something that you ingest every day: table salt is NaCl.
Bromine
Bromine is used as a pesticide. It is also used to flame-proof things. Bromine, like chlorine, is commonly used in disinfectants and sanitizers.
Iodine
Iodine use is very important to the medical community. This is due to its antiseptic qualities. Iodine is often added to halogen headlights that are used in vehicles.
Astatine
Astatine is radioactive and has no known real world applications.
Vocabulary
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Videos
Browse relevant videos from the Journal of Chemical Education's (JCE) Chemistry Comes Alive! library and other video sources.
Chlorine with Acid
Test Tube One and Two:
Test Tube Three and Four:
Comparing the Four Halogens
The reactions in this video are:
F2(g) + Fe(s) → FeF3
F2(g)+ C(s) → CF4
F2(g) + H2(g) → 2HF (g)
H2(g) + Cl2(g) → 2HCl(g)
HCl(g)+ H20(l) → H3O+ + Cl-
2Al(s) +3 F2(g) → 2AlF3
2Al(s) +3 Cl2(g) → 2AlCl3
2Al(s) + 3Br2(g) → 2AlBr3
2Al(s) + 3I2(g) →2 AlI3
Computer Animations
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