That Chicken had a lot of Gall!

Gallium, named after France (or was it a chicken?), lies just west of Germanium in the periodic table. An imaginary (Imaginot?) line separates them. Actually, both Gallium and Germanium are metallic but a clear demarcation runs diagonally east of Germanium, separating the metals from nonmetals--the "haves" and the "have nots" in terms of sharing the electronic wealth:

Once upon a time I briefly worked for an oil company in Cleveland. An older material scientist (whose name escapes me) once showed us interns a neat trick in the lab. He melted some Gallium metal (it melts in your hand) and showed us how a sheet of Aluminum will absorb Gallium (like dissolves like even liquid metals). The older gent, who was a British ex-pat, explained that during WW II, the RAF feared that the Germans would sneak over and sabotage their planes.  In those days, aircraft were often made of unpainted Aluminum.

Here is a video showing how Gallium wrecks an aluminum coke can. Imagine some nefarious kraut doing that to an airplane's wings.

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Actually, Aluminum is not absorbing--rather, Gallium is invading.

The reason that Gallium liquifies is related to why Copper is so ductile and bears repeating: if you give an atom a perfectly filled sub shell along with one extra electron (the 31^st one), the metallic bonding will be weak and non-directional. It all makes perfect sense to me.