code: public void saturate(IAtom atom, IAtomContainer ac) throws CDKException {
          logger.info("Saturating atom by adjusting lone pair electrons...");
          IAtomType atomType = factory.getAtomType(atom.getAtomTypeName());
          int lpCount = (Integer) atomType.getProperty(CDKConstants.LONE_PAIR_COUNT);
          int missingLPs = lpCount - ac.getConnectedLonePairsCount(atom);
  
          for (int j = 0; j < missingLPs; j++) {
              ILonePair lp = atom.getBuilder().newInstance(ILonePair.class, atom);
              ac.addLonePair(lp);
          }
      }
docs: Saturates an IAtom by adding the appropriate number lone pairs.