GC: n
CT: The halogens are five non-metallic elements found in group 17 of the periodic table. The term halogen means “salt-former” and compounds containing halogens are called “salts”. All halogens have 7 electrons in their outer shells, giving them an oxidation number of -1. The halogens exist, at room temperature, in all three states of matter:
- Solid- Iodine, Astatine
- Liquid- Bromine
- Gas- Fluorine, Chlorine.
S: http://www.chemicalelements.com/groups/halogens.html (last access: 5 December 2016 )
N: 1. From Greek hals “salt” (see halo-) + -gen “giving birth to” (see -gen); so called because a salt is formed in reactions involving these four elements. Related: Halogenous.
Frequent use in plural: halogens.
2. A member of a group of five particular chemical elements: Chlorine and iodine are halogens.
3. Halogen element, any of the six nonmetallic elements that constitute Group 17 (Group VIIa) of the periodic table. The halogen elements are fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and element 117 (temporarily named ununseptium [Uus]). They were given the name halogen, from the Greek roots hal- (“salt”) and -gen (“to produce”), because they all produce sodium salts of similar properties, of which sodium chloride—table salt, or halite—is best known.
4. The halogens are five non-metallic elements found in group 17 of the periodic table. The term “halogen” means “salt-former” and compounds containing halogens are called “salts”. All halogens have 7 electrons in their outer shells, giving them an oxidation number of -1.
5. Halogens usually carry a change of -1 (two examples are chlorine and bromine).
S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=halogen (last access: 3 December 2016); BBC – http://www.bbc.co.uk/schools/gcsebitesize/science/add_ocr_gateway/periodic_table/group7rev1.shtml (last access: 5 December 2016). 2. CD – http://dictionary.cambridge.org/dictionary/english/halogen (last access: 3 December 2016 ). 3. EncBrit – https://global.britannica.com/science/halogen-element (last access: 5 December 2016). 4. CE – http://www.chemicalelements.com/groups/halogens.html(last access: 3 December 2016). 5. TERMIUM PLUS – http://goo.gl/2PKANk (last access: 5 December 2016).
SYN: halogen element
S: EncBrit – https://global.britannica.com/science/halogen-element (last access: 5 December 2016), TERMIUM PLUS – http://goo.gl/2PKANk (last access: 5 December 2016).
CR: air pollution, electricity
