On behalf of the ESPAS Task Force, RAND Europe was commissioned to study global societal trends to 2030, and to consider the long-term policy challenges the EU should prioritise for the next institutional cycle (2014-2019) and beyond. The research team focused on five main themes including:
Freebase(0.00 / 0 votes)Rate this definition: Halogen. The halogens or halogen elements are a group in the periodic table consisting of five chemically related elements, fluorine, chlorine, bromine, iodine, and astatine. The artificially created element 117 may also be a halogen. In the modern IUPAC nomenclature, this group is known as group 17. The group of halogens is the only periodic table group which contains elements in all three familiar states of matter at standard temperature and pressure.
The halogen family is a group of reactive nonmetals. 1  Group 17 or VIIA. 2  Halogens. 3  7 valence electrons. 4  reactive nonmetals. 5  melting points and boiling points increase with increasing atomic number. 6  high electron affinities.