+- Forums (https://askaluminium.com)
+-- Forum: My Category (https://askaluminium.com/forumdisplay.php?fid=1)
+--- Forum: aluminium faq (https://askaluminium.com/forumdisplay.php?fid=2)
+--- Thread: Why does aluminium chloride a dimer compound? (/showthread.php?tid=85448)
Why does aluminium chloride a dimer compound? - toyota1515 - 08-02-2022
Aluminium has only 3 valence electrons and therefore forms three single covalent bonds with Chlorine atoms.
But AlCl3 leaves the Aluminium atom with only 6 electrons in its outer shell, rather than the desired Octet.
But each AlCl3 molecule contains three Chlorine atoms that have lone pairs of electrons uninvolved in bonding. So, a dative or coordinate bond forms from a Chlorine atom on one molecule to the Aluminium on the other. Consequently, the molecules pair up or dimerise so that each Aluminium atom has a share of eight electrons in its outer shell.