Extended molecular graph construction Given the predicted number of lone pairs and their types per atom, the pipeline continues toward the construction of the extended molecular graph G ext . As previously mentioned, the nodes in the extended graph do not represent only atoms but also lone pairs and bonds. Even though these two nodes do not represent atoms, we opted to design the graph as homogeneous rather than heterogeneous. Next, predicted lone pair nodes were connected to the respective atom node, carrying features such as its type (σ-or π-), and distance from the parent atom. Finally, we created the bond nodes representing different bonds between two atoms. Each pair of atoms is connected to the number of bond nodes corresponding to the bond order. The neural network architecture comprises two parts (shown in Figure ): the node encoder and a group of multiple separate MLPs. The latter make predictions using the embeddings from the encoder part, but multiple preprocessing steps may be conducted depending on the task.