code: public boolean allHeavyAtomsPlaced(IAtomContainer ac) {
          for (int i = 0; i < ac.getAtomCount(); i++) {
              if (isUnplacedHeavyAtom(ac.getAtom(i))) {
                  return false;
              }
          }
          return true;
      }
docs: True is all the atoms in the given AtomContainer have been placed.
  
  @param  ac  The AtomContainer to be searched
  @return     True is all the atoms in the given AtomContainer have been placed