Halogen: Difference between revisions

Revision as of 01:39, 14 March 2007

Revision as of 01:42, 14 March 2007

Line 33:

=== Oxidation states ===

Halogens are by default, one electron less than that of a noble gas, and to obtain a stable structure require an electron to be recieved through bonding or ionisation of another element to produce a negative ion (<math>X_{(g)} + e^- \rightarrow X^-_{(g)}</math>) through an [[exothermic]] reaction.<ref name="holl_312">Holliday, C., Chambers, A. K. (1975), p 312</ref> There are numerous [[ionic]]ally-bonded halogen compounds, but the majority of those which form [[noble gas]] configurations, formas themwell as covalent compounds formed through covalent bonds with other halogens of non-polar electronegative elements. Under normal conditions, the formation of halogen ions can only usually result in a single negative charge and oxidation state, due to the completion of it's outer shell and the amount of energy required to promote an element's structure to it's next shell by electron gain.<ref name="holl_311">Holliday, C., Chambers, A. K. (1975), p 311</ref><ref name="holl_313">Holliday, C., Chambers, A. K. (1975), p 313</ref> For instance, the gain of electrons in the structure of [[fluorine]] to yield it's [[3|electron shell]][[Sub-shell|s]] requires significantly higher amounts of energy than found under "normal conditions".<ref name="chem_800">Greenwood, N. N.,Earnshaw, A. (1997), p800</ref>

However, because of unfilled ''d'' orbitals in halogens, they are still available for covalency and can contribute towards the formation of compounds formed from other halogens and oxygen, which can achieve oxidation states as high as +7, such as those observed in chlorate I, V, and VII anions (ClO^-, ClO₃^- and ClO₄^-).<ref name="holl_311" /><ref name="holl_312" /><ref name="chem_800" />