code: private IAtomContainer getUnplacedAtoms(IAtom atom) {
          IAtomContainer unplacedAtoms = atom.getBuilder().newInstance(IAtomContainer.class);
          List bonds = molecule.getConnectedBondsList(atom);
          IAtom connectedAtom;
          for (int f = 0; f < bonds.size(); f++) {
              connectedAtom = ((IBond) bonds.get(f)).getOther(atom);
              if (!connectedAtom.getFlag(CDKConstants.ISPLACED)) {
                  unplacedAtoms.addAtom(connectedAtom);
              }
          }
          return unplacedAtoms;
      }
docs: Returns an AtomContainer with all unplaced atoms connected to a given
  atom
  
  @param atom The Atom whose unplaced bonding partners are to be returned
  @return an AtomContainer with all unplaced atoms connected to a
  given atom