code: @Override
      public IElectronContainer getElectronContainer(int number) {
          if (number < this.bondCount) return bonds[number];
          number -= this.bondCount;
          if (number < this.lonePairCount) return lonePairs[number];
          number -= this.lonePairCount;
          if (number < this.singleElectronCount) return singleElectrons[number];
          return null;
      }
docs: {@inheritDoc}