What is it about certain metals that make them toxically dangerous while others aren’t? I mean, I’ve always heard of the danger of “heavy metals” like lead and some others. But is it just the atomic weight of a metal that determines if it is toxic? Beryllium certainly isn’t high in the heavyweight category.
I don’t think that there’s any universal toxicity pattern. There seem to be a lot of ways that they can poison you.
If you consider the periodic table as a whole and take away those elements which are used by the body (mostly the lower-numbered elements since these are more common) and those which are chemically nonreactive (the noble gases), the remaining ones are mostly pretty dangerous, and mostly metals.
There is one semi-common poisoning path that I can think of, which is that some elements can replace others because they behave similarly chemically. For instance, calcium in your bones can be replaced with lead or cadmium. Your body doesn’t have much of a natural defense against this happening because they aren’t that common in pure form. And unfortunately, while they are *similar *chemically, they aren’t identical, and so it ends up weakening your bones.
I have a few pounds of bismuth, too, as broken ingot. It is diamagnetic enough that a bismuth plumb bob hung near a powerful magnet will stay barely visibly out of plumb due to repelling the magnet. Diamagnetism is not the sort of thing you expect to be able to see working with your own eyes.
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If you cut yourself with a piece of beryllium (the example he gave was a beryllium watch spring), the wound will not heal (or will be very slow to heal).
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I knew a guy who many years ago, sliced his finger on a BeCu motor brush spring or something along those lines, and it left him a weird divot in the side of the finger, so the stuff is apparently toxic on internal contact regardless of how safe it may be to touch it with unbroken skin.