Halogen example sentences

It is due to the absence of d orbitals that the maximum covalence of B is Since the d orbitals are available with Al and other elements, the maximum covalence can be expected beyond Most of the other metal halides (e.g., AlCl3) are dimerised through halogen bridging (e.g., Al2Cl6).They are the halogens (Group 17) and the chalcogens (Group 16).It is observed that for halogens, the rate is: iodine > bromine > chlorine, while for alkyl groups it is : tert > secondary > primary.Replacement of halogenated solvent by liquid CO2 will result in less harm to ground water.The metal species completes its octet by accepting electrons from halogen in these halogen bridged molecules.It resists the attack by halogens, dihydrogen and most of the acids and metals even at elevated temperatures.Likewise within a group of representative metals (say alkali metals) reactivity increases on moving down the group, whereas within a group of non-metals (say halogens), reactivity decreases down the group.Addition of halogens to alkenes is an example of electrophilic addition reaction involving cyclic halonium ion formation which you will study in higher classes.Tropospheric pollution is basically due to various oxides of sulphur, nitrogen, carbon, halogens and also due to particulate pollutants.The chemical reactivity of an element can be best shown by its reactions with oxygen and halogens.Like addition of halogens to alkenes, addition of hydrogen halides is also an example of electrophilic addition reaction.This is example of ?-elimination reaction, since hydrogen atom is eliminated from the ? carbon atom (carbon atom next to the carbon to which halogen is attached).To restore the aromatic character, ? -complex releases proton from sp3 hybridised carbon on attack by [AlCl4]– (in case of halogenation, alkylation and acylation) and [HSO4]– (in case of nitration).This reaction is known as dehydrohalogenation i.e., removal of halogen acid.Arenes react with halogens in the presence of a Lewis acid like anhydrous FeCl3, FeBr3 or AlCl3 to yield haloarenes.