Also  now I tend, as you've  probably come to realise  I've tended to include  specific types of bonding arrangements  as a functional group  for example, I call  a carbon carbon double bond, I call that a functional group  for the simple reason that that arrangement of bonds dictates  the principle properties of those compounds  and in that context I'm then using the word group a bit more liberally  instead of saying it's a group of atoms  which dictate  the properties  I'll say it's a group of atoms or  it's a special grouping of electrons, which dictate the properties.