chemical behaviour of the first member of a group of

Last updated: 7/4/2023

chemical behaviour of the first member of a group of elements in the s and p blocks compared to that of the subsequent members in the same group The anomalous behaviour is attributed to their small size large charge radius ratio and high electronegativity of the elements In addition the first member of group has only four valence orbitals 2s and 2p available for bonding whereas the second member of the groups have nine valence orbitals 3s 3p 3d As a consequence of this the maximum covalency of the first member of each group is 4 e g boron can only form B 88 Al 143 BF4 whereas the other members of the groups can expand their valence shell to accommodate more than four pairs of electrons e g aluminium AlF forms Furthermore the first member of p block elements displays greater ability to form p P multiple bonds to itself e g C C C C N N N N and to other second period elements e g C O C N C N N O compared to subsequent members of the same group