Also which element has the greater tendency to retain electrons, copper or hydrogen?
Definitely Hydrogen. The radii of copper is longer than Hydrogen and that leads to a higher shielding effect. Shielding effect means inner electrons are block and therefore copper atoms can easily lose electrons to become octet. Besides, Hydrogen atoms have a high ionization energy (1312.0 KJ/mole). Ionization energy refers a force needed to lose an electrons. The higher ionization energy, the harder to lose electrons. I hope it helps and I am glad! Because I am not an expert in this field!!=]
