What element never obeys the ''octet rule'' when covalently bonding?

1 Answer

I'm guessing that one element that never obeys the octet rule when bonding is beryllium. Beryllium has only 2 valence electrons for bonding.

Another element that does not follow the octet rule is boron. Boron does share electrons, but it has only three valence electrons. #BCl_3# is a molecule that is trigonal planar in nature. Each of boron's valence electrons is shared by a chlorine, thus you have 6 shared electrons in the Lewis dot structure. Scientists say that #BCl_3# behaves as if it is "electron deficient." Not sure what that means, but an octet is not formed.