Answer:
Lithium loses one electron to become an ion.
Just in case they have to land in the ocean in case of an emergency
At the end, Dade and Julian both feel very lonely in the world, but in very different ways. Julian feels alone physically
Yes, I believe she would be welcoming. Even though the last part of the poem sounds like a curse ("<span>May the young man be sad-minded with hard heart-thoughts"), it is still a statement of the speaker's enduring love for him. She suffers, but imagines that he suffers too, in the exile or wherever he is, and remembers their happy days with sorrow. Her depression has elements of embitteredness, but her love for him is not disputable.</span>
Walked because its what he's doing