Homologous structures are those that have the same evolutionary origin but fulfill very different functions, a good example could be the wing of a bird and the wing of an insect, the wings of birds, are modified front members and the wings of insects are "BRANCHES" modified
In the case of maple and oak leaves they are homologous structures because they have a common ancestor according to their genetic decoding, that is, even if they can look different or behave differently, they are genetically homologous structures.
This gives each hydrogen atom two electrons in its outer energy level, which is full. It also gives oxygen 8 electrons in its outer energy level, which is also full.
